Please select the eligibility criteria that correspond to the clinical trial below.
Title: A Multi-Centre, Multinational, Long-Term Extension Study, to Assess the Safety and Toleration of Subject Optimised Treatment Regimens of Oral Sildenafil Citrate for Pulmonary Arterial Hypertension in Subjects Who Have Completed Study A1481140.
Brief Summary: Open label extension study to the pivotal efficacy study to assess the safety of sildenafil citrate in patients with pulmonary arterial hypertension


Options:
A: Inclusion Criteria:

* Treatment for PAH with sildenafil at a dose of 20mg tid or greater for at least 30 days
* Clinical decision to convert from sildenafil to tadalafil therapy
* Patient consents to study participation (for patients who have already transitioned from sildenafil to tadalafil therapy prior to study initiation or identification of the patient, if the patient has provided consent for use of their medical record for research, retrospective review of the transition process will be performed. When possible, these patients will be approached about prospective data collection for the study if the transition occurred less than 3 months prior to consideration of prospective study participation)

Exclusion Criteria:

* Non-group I PAH
* Age less than 18
B: Inclusion Criteria:

* Patients with PAH who had completed the 12 week pivotal study

Exclusion Criteria:

* Any other patients with PAH that had not been included into the pivotal study
C: Inclusion Criteria:

1. Signed informed consent prior to initiation of any study mandated procedure.
2. Patients with symptomatic pulmonary arterial hypertension (PAH) in modified World Health Organization (WHO) functional class II to IV.
3. Patients with the following types of pulmonary arterial hypertension (PAH) belonging to groups 1.1 to 1.3 of the Venice classification:

   * Idiopathic (IPAH);
   * Familial (FPAH); or
   * Related to:

     * Collagen vascular disease;
     * Simple, congenital systemic-to-pulmonary shunts at least 1 year post surgical repair;
     * Human immunodeficiency virus (HIV) infection; or
     * Drugs and toxins.
4. PAH diagnosis confirmed by hemodynamic evaluation performed prior to randomization and showing all of the following:

   * Mean pulmonary artery pressure (mPAP) \> 25 mmHg at rest;
   * Pulmonary capillary wedge pressure (PCWP) or left ventricular end diastolic pressure (LVEDP) \< 15 mmHg; and
   * Pulmonary vascular resistance (PVR) at rest \>= 320 dyn×sec/cm\^5.
5. 6-minute walk distance (6MWD) \>= 50 m.
6. Men or women \> 12 years of age (women of childbearing potential must have a negative pre-treatment serum pregnancy test and must use a reliable method of contraception).

Exclusion Criteria:

1. PAH associated with portal hypertension, thyroid disorders, glycogen storage disease, Gaucher''s disease, hereditary hemorrhagic telangiectasia, hemoglobinopathies, myeloproliferative disorders or splenectomy.
2. PAH associated with non corrected simple congenital systemic-to-pulmonary shunts, and combined and complex systemic-to-pulmonary shunts, corrected or non corrected.
3. PAH associated with significant venous or capillary involvement (PCWP \> 15 mmHg), known pulmonary veno-occlusive disease, and pulmonary capillary hemangiomatosis.
4. Persistent pulmonary hypertension of the newborn.
5. Pulmonary Hypertension belonging to groups 2 to 5 of the Venice classification.
6. Moderate to severe obstructive lung disease: forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) \< 70% and FEV1 \< 65% of predicted value after bronchodilator administration.
7. Moderate to severe restrictive lung disease: total lung capacity (TLC) \< 60% of predicted value.
8. Moderate to severe hepatic impairment, i.e., Child-Pugh Class B or C.
9. Estimated creatinine clearance \< 30 mL/min
10. Serum aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) \> 1.5 times the upper limit of normal.
11. Hemoglobin \< 75% of the lower limit of the normal range.
12. Systolic blood pressure \< 100 mmHg.
13. Acute or chronic physical impairment (other than dyspnea), limiting the ability to comply with study requirements.
14. Pregnant or breast-feeding.
15. Known concomitant life-threatening disease with a life expectancy \< 12 months.
16. Body weight \< 40 kg.
17. Any condition that prevents compliance with the protocol or adherence to therapy.
18. Recently started (\< 8 weeks prior to randomization) or planned cardio-pulmonary rehabilitation program based on exercise.
19. Treatment with endothelin receptor antagonists (ERAs) within 3 months prior to randomization.
20. Systemic treatment within 4 week prior to randomization with cyclosporine A or tacrolimus, everolimus, sirolimus (calcineurin or mammalian target of rapamycin (mTOR) inhibitors).
21. Treatment with cytochrome P3A (CYP3A) inducers within 4 weeks prior to randomization
22. Known hypersensitivity to drugs of the same class as the study drug, or any of their excipients.
23. Planned treatment, or treatment, with another investigational drug within 1 month prior to randomization.
D: Inclusion Criteria:

* Clinical diagnosis of IPF
* 40-85 years of age
* 6-minute walk distance 150-500 m
* FVC 40-90% predicted
* DLCO 30-90% predicted

Exclusion Criteria:

* Severe pulmonary hypertension
* Severe heart failure
* FEV1/FVC \< 0.7

Answer: B