This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pathology of Conception, Subject name: Gynaecology & Obstetrics
[{'content': 'Inhibin B levels as test of ovarian reserve is best measured on? \nSelect and explain. \nA. Day 2 of menstruation, B. Day 3 of menstruation, C. Day 4 of menstruation, D. Day 5 of menstruation', 'role': 'user'}, {'content': "Answer: B \nExplanation: ANSWER: (B) Day 3 of menstruationREF: Novaks gyn 12th edp. 406'Cycle day 3 is chosen because at this time the estrogen level is expected to be low, a critical feature, as FSH levels are subject to a negative feedback'Tests for ovarian reserveDay of testingFSH (most commonly used)Day 3Clomiphene citrate challenge test (CCCT)Day 3Serum inhibin BDay 3Transvaginal ultrasound to assess antral follicle number or ovarian sizeAny", 'role': 'assistant'}]