Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Phase 4 Randomized, Double-Blind, Placebo-Controlled, Multicenter Study Evaluating The Efficacy And Safety Of Re-Treatment With Varenicline In Subjects Who Are Currently Smoking, And Who Have Previously Taken Varenicline
Brief Summary: The main purpose of this study is to compare the effectiveness and safety of the re-treatment of smokers with varenicline with placebo for smoking cessation during the last 4 weeks of a 12 week course of treatment. The study will also assess whether smokers remain abstinent at Week 24 (12 weeks after the end of treatment) and Week 52 (40 weeks after the end of treatment).


Options:
A: Inclusion Criteria:

* Age 18 years or older
* English speaking
* Smoked at least 100 cigarettes/lifetime
* Smoke 5 or more cigarettes per day
* Interested in quitting smoking (preparation or contemplation stage of change)
* Enrolled in Einstein/Montefiore methadone program for 12 weeks or more
* Receiving methadone in clinic three, four, five or six times per week
* No more than 2 methadone clinic misses in prior 14 days
* Agree to use contraception for the duration of the trial (among women with reproductive potential)
* Willing to participate in all study components
* Able to provide informed consent

Exclusion Criteria:

* Serious or unstable HIV/AIDS, liver, cardiovascular, or pulmonary disease
* Psychiatric instability
* Women who are pregnant, breastfeeding, or contemplating pregnancy
* Creatinine clearance \<30 mL/min
B: Inclusion Criteria:

* Long-term, daily NRT users (except nicotine patch) (\>11 months) ex-smokers that are willing to try to stop the use of NRT and adhere to this protocol.
* More than 4 pieces of nicotine gum/ sublingual tablets/ lozenges/ per day, OR more than 3 inhaler cylinders per day, OR
* more than 10 puffs of nasal spray per day.

Exclusion Criteria:

* Age \< 18 years,
* CO Smokers,
* Pregnant and lactating women,
* Used varenicline before,
* Not able to cooperate,
* Other significant diseases that might influence the trial (such as moderate -severe cardiac disease, lung cancer,) in expired air \> 7 ppm.
C: Inclusion Criteria:

* Subjects must have smoked an average of at least 10 cigarettes per day during the past year and over the month prior to the screening visit, with no period of abstinence greater than 3 months in the past year.

Exclusion Criteria:

* Subjects with clinically significant, recent cardiovascular disease.
D: Inclusion Criteria:

* Smokers aged 18 years or above and wanting to stop smoking
* Smokers who have smoked an average of at least 10 cigarettes per day over the last 4 weeks
* Smokers who have tried before to stop smoking at least once with varenicline, and who took varenicline for at least 2 weeks
* The last attempt to stop smoking must be at least 3 months before entering the study

Exclusion Criteria:

* Individuals who have not tolerated varenicline well previously, or who have a current or prior medical or psychiatric history that would make entry into the trial inadvisable
* Individuals who have previously participated in clinical trials of varenicline
* Individuals who have been participating in another smoking cessation trial within the last 3 months, or other drug trial within the last 30 days

Answer: D