This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
Sourse of progesterone during normal mestrual cycle : 
Select and explain. 
A. Corpus luteum, B. Stroma, C. Surface epithelium of ovary, D. None
A: Corpus luteum
Answer: A: Corpus luteum 
Explanation: Corpus luteum