This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Contraceptives, Subject name: Gynaecology & Obstetrics
[{'content': 'Not a barrier contraceptive: \nSelect and explain. \nA. Diaphragm, B. Centchroman, C. Condom, D. Today', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is b, i.e. CentchromanRef: 15th/ed, p222Barrier Methods include:* Condoms (for male use)* Diaphragms (for female use) - Types1. Femshield (female condom)2. Today contraceptive/vaginal sponge3. Vaginal diaphragm/cervical capBesides these spermicidal agents like nonoxynol 9, octoxynol, and menfegol can be added to any of the above barrier contraceptive, to increase its effectiveness.', 'role': 'assistant'}]