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
The male sex hormone testosterone is produced by: 
Select and explain. 
A. Sertoli cells, B. Epithelial cells, C. Interstitial cells of leydig, D. Primitive germ cells
C: Interstitial cells of leydig
Answer: C: Interstitial cells of leydig 
Explanation: None