This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Natural Methods, Barrier Methods, IUDs, OCPs, Subject name: Social & Preventive Medicine
Non hormonal Pill - Centchroman is taken orally: 
Select and explain. 
A. Daily for first three months and then once-a-week, B. Twice a week for the first three months and then once-a-week, C. Thrice a week for the first three months and then once-a-week, D. Twice a week for the first five months and then once-a-week
B: Twice a week for the first three months and then once-a-week
Answer: B: Twice a week for the first three months and then once-a-week 
Explanation: - Centchroman is a selective estrogen receptor modulators or SERMs, a class of medication which acts on the estrogen receptor. - It is best known as a nonsteroidal oral contraceptive. - Centchroman is a weekly pill that needs to be taken twice a week for the first 3 months and then once a week. - Its effect begins after a month.