user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: what medical trial design using health study has the lowest number of expected total enrollment? 
Knowledge Triplets: Hypertension Prevention Trial (HPT) Feasibility Study, medicine.medical_trial.sponsor, National Heart, Lung, and Blood Institute
Interventional, medicine.medical_trial_type.medical_trials, A Phase I Evaluation of Azidothymidine (AZT) in Children with Acquired Immune Deficiency Syndrome (AIDS) or AIDS Related Complex (ARC)
Physicians' Health Study, medicine.medical_trial.treatment_being_tested, Aspirin
Cardiovascular disease, medicine.disease.medical_specialties, Interventional radiology
Interventional, medicine.medical_trial_type.medical_trials, Nimotuzumab in Adults With Glioblastoma Multiforma
Coronary artery disease, medicine.disease.trials, Physicians' Health Study
Prevention, medicine.medical_trial_design.trials, Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up
Blind experiment, medicine.medical_trial_design.trials, Physicians' Health Study
Blind experiment, medicine.medical_trial_design.trials, Rapid Evaluation of Amantadine for Treatment of Cocaine Abuse/Dependence – 4
Interventional, medicine.medical_trial_type.medical_trials, A Study of Zidovudine in HIV-Infected Patients With Liver Disease
Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up, medicine.medical_trial.type_of_trial, Interventional
Interventional, medicine.medical_trial_type.medical_trials, Amoxicillin for the Treatment of Pediatric Autoimmune Disorders Associated With Streptococcal Infections
Coronary artery disease, medicine.disease.trials, Postmenopausal Hormone Therapy in Unstable Angina
Interventional, medicine.medical_trial_type.medical_trials, A Study of Atvogen in Healthy Volunteers and HIV-Infected Patients Who Have No Symptoms of Infection
Physicians' Health Study, medicine.medical_trial.clinicaltrials_identifier, NCT00000500
Methadone Effects on Zidovudine (ZDV, AZT) Disposition, medicine.medical_trial.type_of_trial, Interventional
A Study of Two Anti-HIV Drug Combinations in HIV-Infected Patients, medicine.medical_trial.type_of_trial, Interventional
Blind experiment, medicine.medical_trial_design.trials, A Study of Atvogen in Healthy Volunteers and HIV-Infected Patients Who Have No Symptoms of Infection
Interventional, medicine.medical_trial_type.medical_trials, Safety and Effectiveness of Giving Indinavir Plus Stavudine Plus Lamivudine to HIV-Infected Children
Behavioral Insomnia Therapy With Chronic Fatigue Syndrome, medicine.medical_trial.design, Randomized
National Heart, Lung, and Blood Institute, medicine.medical_trial_sponsor.trials_sponsored, Hypertension Prevention Trial (HPT) Feasibility Study
Randomized, medicine.medical_trial_design.trials, Memantine in Systemic Lupus Erythematosus
Interventional, medicine.medical_trial_type.medical_trials, Phase II Trial of Sequential Chemotherapy and Radiotherapy for AIDS- Related Primary Central Nervous System Lymphoma
Interventional, medicine.medical_trial_type.medical_trials, Hypertension Prevention Trial (HPT) Feasibility Study
Myocardial Ischemia, medicine.disease.trials, Physicians' Health Study
m.0gvp_65, dataworld.gardening_hint.last_referenced_by, Blind experiment
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.diseases, Cardiovascular disease
Blind experiment, medicine.medical_trial_design.trials, Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder
Interventional, medicine.medical_trial_type.medical_trials, Feasibility Study of Take-Home LAAM Medication – 3
National Heart, Lung, and Blood Institute, medicine.medical_trial_sponsor.trials_sponsored, Postmenopausal Hormone Therapy in Unstable Angina
Carotene, medicine.medical_treatment.trials, Physicians' Health Study
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.design, Prevention
Physicians' Health Study, medicine.medical_trial.eligibility_exclusion_criteria, No history of stroke, myocardial infarction, cancer, or renal disease.
Feasibility Study of Take-Home LAAM Medication – 3, medicine.medical_trial.type_of_trial, Interventional
Myocardial Ischemia, medicine.disease.medical_specialties, Family medicine
m.040ftkg, dataworld.gardening_hint.replaced_by, Blind experiment
Cardiovascular disease, medicine.disease.medical_specialties, Vascular surgery
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.design, Blind experiment
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.design, Randomized
Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder, medicine.medical_trial.type_of_trial, Interventional
Hypertension Prevention Trial (HPT) Feasibility Study, medicine.medical_trial.design, Prevention
Interventional, medicine.medical_trial_type.medical_trials, Physicians' Health Study
III, medicine.medical_trial_phase.medical_trials, Physicians' Health Study
Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up, medicine.medical_trial.diseases, Cardiovascular disease
Physicians' Health Study, medicine.medical_trial.eligibility_exclusion_criteria, No contraindications to aspirin or beta-carotene
Interventional, medicine.medical_trial_type.medical_trials, Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up
Physicians' Health Study, medicine.medical_trial.maximum_age_for_eligibility, 84
Randomized, medicine.medical_trial_design.trials, Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up
A Phase I Evaluation of Azidothymidine (AZT) in Children with Acquired Immune Deficiency Syndrome (AIDS) or AIDS Related Complex (ARC), medicine.medical_trial.type_of_trial, Interventional
Nimotuzumab in Adults With Glioblastoma Multiforma, medicine.medical_trial.type_of_trial, Interventional
Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder, medicine.medical_trial.design, Randomized
Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder, medicine.medical_trial.phase, III
Blind experiment, medicine.medical_trial_design.trials, The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome
Physicians' Health Study, medicine.medical_trial.minimum_age_for_eligibility, 40
Physicians' Health Study, medicine.medical_trial.diseases, Cardiovascular disease
Oral Collagen for Rheumatoid Arthritis, medicine.medical_trial.type_of_trial, Interventional
Physicians' Health Study, medicine.medical_trial.design, Randomized
The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome, medicine.medical_trial.type_of_trial, Interventional
Hypertension Prevention Trial (HPT) Feasibility Study, medicine.medical_trial.design, Randomized
Rapid Evaluation of Amantadine for Treatment of Cocaine Abuse/Dependence – 4, medicine.medical_trial.design, Blind experiment
Prevention, medicine.medical_trial_design.trials, Physicians' Health Study
Blind experiment, medicine.medical_trial_design.trials, Memantine in Systemic Lupus Erythematosus
Cardiovascular disease, medicine.disease.trials, Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up
Memantine in Systemic Lupus Erythematosus, medicine.medical_trial.design, Blind experiment
double-blind procedure.noun.01, base.wordnet.synset.equivalent_topic, Blind experiment
Interventional, medicine.medical_trial_type.medical_trials, The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome
Physicians' Health Study, medicine.medical_trial.diseases, Myocardial Ischemia
Amoxicillin for the Treatment of Pediatric Autoimmune Disorders Associated With Streptococcal Infections, medicine.medical_trial.type_of_trial, Interventional
Interventional, medicine.medical_trial_type.medical_trials, Methadone Effects on Zidovudine (ZDV, AZT) Disposition
III, medicine.medical_trial_phase.medical_trials, The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome
Randomized, medicine.medical_trial_design.trials, Oral Collagen for Rheumatoid Arthritis
double blind.noun.01, base.wordnet.synset.equivalent_topic, Blind experiment
Physicians' Health Study, medicine.medical_trial.type_of_trial, Interventional
Randomized, medicine.medical_trial_design.trials, Postmenopausal Hormone Therapy in Unstable Angina
Blind experiment, base.schemastaging.context_name.pronunciation, g.125_nd2r8
Interventional, medicine.medical_trial_type.medical_trials, Oral Collagen for Rheumatoid Arthritis
Interventional, medicine.medical_trial_type.medical_trials, Memantine in Systemic Lupus Erythematosus
Cardiovascular disease, medicine.disease.medical_specialties, Cardiology
Safety and Effectiveness of Giving Indinavir Plus Stavudine Plus Lamivudine to HIV-Infected Children, medicine.medical_trial.type_of_trial, Interventional
Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up, medicine.medical_trial.design, Randomized
Cardiovascular disease, medicine.disease.trials, Postmenopausal Hormone Therapy in Unstable Angina
III, medicine.medical_trial_phase.medical_trials, Postmenopausal Hormone Therapy in Unstable Angina
The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome, medicine.medical_trial.design, Randomized
Physicians' Health Study, medicine.medical_trial.eligibility_exclusion_criteria, No current usage of aspirin or Vitamin A tables greater than once per week.
Oral Collagen for Rheumatoid Arthritis, medicine.medical_trial.design, Randomized
A Study of Atvogen in Healthy Volunteers and HIV-Infected Patients Who Have No Symptoms of Infection, medicine.medical_trial.type_of_trial, Interventional
Randomized, medicine.medical_trial_design.trials, Alendronate and/or Parathyroid Hormone for Osteoporosis
Physicians' Health Study, medicine.medical_trial.design, Prevention
Interventional, medicine.medical_trial_type.medical_trials, Cocaine Effects in Humans: Physiology and Behavior – 1
Prevention, medicine.medical_trial_design.trials, Hypertension Prevention Trial (HPT) Feasibility Study
Physicians' Health Study, medicine.medical_trial.eligibile_genders, Male
Aspirin, medicine.medical_treatment.trials, Physicians' Health Study
Myocardial Ischemia, medicine.disease.medical_specialties, Internal medicine
Physicians' Health Study, medicine.medical_trial.sponsor, National Heart, Lung, and Blood Institute
Behavioral Insomnia Therapy With Chronic Fatigue Syndrome, medicine.medical_trial.type_of_trial, Interventional
Phase II Trial of Sequential Chemotherapy and Radiotherapy for AIDS- Related Primary Central Nervous System Lymphoma, medicine.medical_trial.type_of_trial, Interventional
Randomized, medicine.medical_trial_design.trials, Hypertension Prevention Trial (HPT) Feasibility Study
Hypertension Prevention Trial (HPT) Feasibility Study, medicine.medical_trial.diseases, Cardiovascular disease
Pharmacological Modulation of Cocaine Effects – 1, medicine.medical_trial.type_of_trial, Interventional
Cardiovascular disease, medicine.disease.trials, Physicians' Health Study
Interventional, medicine.medical_trial_type.medical_trials, Pharmacological Modulation of Cocaine Effects – 1
Coronary artery disease, medicine.disease.medical_specialties, Cardiac surgery
Cocaine Effects in Humans: Physiology and Behavior – 1, medicine.medical_trial.type_of_trial, Interventional
Physicians' Health Study, medicine.medical_trial.phase, III
Physicians' Health Study, medicine.medical_trial.treatment_being_tested, Carotene
Randomized, medicine.medical_trial_design.trials, Physicians' Health Study
Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up, medicine.medical_trial.sponsor, National Heart, Lung, and Blood Institute
Randomized, medicine.medical_trial_design.trials, Rapid Evaluation of Amantadine for Treatment of Cocaine Abuse/Dependence – 4
Cardiovascular disease, medicine.disease.medical_specialties, Thoracic surgery
Randomized, medicine.medical_trial_design.trials, The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome
Hypertension Prevention Trial (HPT) Feasibility Study, medicine.medical_trial.type_of_trial, Interventional
Randomized, medicine.medical_trial_design.trials, Behavioral Insomnia Therapy With Chronic Fatigue Syndrome
Rapid Evaluation of Amantadine for Treatment of Cocaine Abuse/Dependence – 4, medicine.medical_trial.design, Randomized
Coronary artery disease, medicine.disease.medical_specialties, Internal medicine
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.diseases, Coronary artery disease
Interventional, medicine.medical_trial_type.medical_trials, A Study of Two Anti-HIV Drug Combinations in HIV-Infected Patients
Cardiovascular disease, medicine.disease.medical_specialties, Internal medicine
Physicians' Health Study, medicine.medical_trial.start_date, 1981-09
Blind experiment, medicine.medical_trial_design.trials, Postmenopausal Hormone Therapy in Unstable Angina
Interventional, medicine.medical_trial_type.medical_trials, Alendronate and/or Parathyroid Hormone for Osteoporosis
Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder, medicine.medical_trial.design, Blind experiment
Coronary artery disease, medicine.disease.medical_specialties, Family medicine
Cardiovascular disease, medicine.disease.trials, Hypertension Prevention Trial (HPT) Feasibility Study
Memantine in Systemic Lupus Erythematosus, medicine.medical_trial.design, Randomized
Cardiovascular disease, medicine.disease.medical_specialties, Neurology
Prevention, medicine.medical_trial_design.trials, Postmenopausal Hormone Therapy in Unstable Angina
Interventional, medicine.medical_trial_type.medical_trials, Postmenopausal Hormone Therapy in Unstable Angina
National Heart, Lung, and Blood Institute, medicine.medical_trial_sponsor.trials_sponsored, Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up
A Study of Atvogen in Healthy Volunteers and HIV-Infected Patients Who Have No Symptoms of Infection, medicine.medical_trial.design, Blind experiment
Nimotuzumab in Adults With Glioblastoma Multiforma, medicine.medical_trial.phase, III
The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome, medicine.medical_trial.phase, III
Alendronate and/or Parathyroid Hormone for Osteoporosis, medicine.medical_trial.design, Randomized
Myocardial Ischemia, medicine.disease.medical_specialties, Cardiology
Physicians' Health Study, medicine.medical_trial.diseases, Coronary artery disease
A Study of Zidovudine in HIV-Infected Patients With Liver Disease, medicine.medical_trial.type_of_trial, Interventional
Physicians' Health Study, medicine.medical_trial.design, Blind experiment
Interventional, medicine.medical_trial_type.medical_trials, Behavioral Insomnia Therapy With Chronic Fatigue Syndrome
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.type_of_trial, Interventional
Interventional, medicine.medical_trial_type.medical_trials, Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder
Coronary artery disease, medicine.disease.medical_specialties, Cardiology
Cardiovascular disease, medicine.disease.medical_specialties, Family medicine
Randomized, medicine.medical_trial_design.trials, Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder
The Study of the Safety and Efficacy of Ampligen in Chronic Fatigue Syndrome, medicine.medical_trial.design, Blind experiment
III, medicine.medical_trial_phase.medical_trials, Efficacy and Safety of SPD417 in Treatment of Manic Symptoms in Adults With Bipolar I Disorder
Physicians' Health Study, medicine.medical_trial.eligibility_inclusion_criteria, Male physicians
Alendronate and/or Parathyroid Hormone for Osteoporosis, medicine.medical_trial.type_of_trial, Interventional
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.sponsor, National Heart, Lung, and Blood Institute
Vitamin E and C to Slow Progression of Common Carotid Artery Plaque Build-up, medicine.medical_trial.design, Prevention
III, medicine.medical_trial_phase.medical_trials, Nimotuzumab in Adults With Glioblastoma Multiforma
National Heart, Lung, and Blood Institute, medicine.medical_trial_sponsor.trials_sponsored, Physicians' Health Study
Postmenopausal Hormone Therapy in Unstable Angina, medicine.medical_trial.phase, III
Memantine in Systemic Lupus Erythematosus, medicine.medical_trial.type_of_trial, Interventional

Answer: Randomized
Blind experiment