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: Physiology
Progesterone production in the ovary is primarily by: 
Select and explain. 
A. Stroma, B. Corpora albicans, C. Corpora lutea, D. Mature follicles
C: Corpora lutea
Answer: C: Corpora lutea 
Explanation: None