This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Reproductive physiology and hormones in females, Subject name: Gynaecology & Obstetrics
[{'content': 'Peak level of plasma progesterone in the luteal phase : \nSelect and explain. \nA. 1ng/ml, B. 10ng/ml, C. 15ng/ml, D. 30ng/ml', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Serum values of Progesterone : Follicular Phase: < 1 ng/ml Midluteal phase: 5-15 ng/ml (day 22nd of menstrual cycle) Reference: Clinical Endocrinologic Gynecology and Infeility, Eighth edition; Chapter 6', 'role': 'assistant'}]