This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Gynaecology & Obstetrics
[{'content': 'Superfecundation refers to \nSelect and explain. \nA. Feilization of one ovum with two spermatozoa, B. Feilization of two ova in the same menstrual cycle, C. Feilization of two ova in different menstrual cycles, D. Feilization of three ova in the same menstrual cycle', 'role': 'user'}, {'content': "Answer: B \nExplanation: Mechanism of monozygotic twinning:The outcome of the monozygotic twinning process depends on when division occurs. If zygotes divide within the first 72 hours after feilization, two embryos, two amnions, and two chorions develop, and a diamniotic, dichorionic twin pregnancy evolves.If division occurs between the fouh and eighth day, a diamniotic, monochorionic twin pregnancy results. By approximately 8 days after feilization, the chorion and the amnion have already differentiated, and division results in two embryos within a common amniotic sac, that is, a monoanionic, monochorionic twin pregnancy. Conjoined twins result if twinning is initiated later.(Ref: William's Obstetrics; 25th edition)", 'role': 'assistant'}]