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
Which one of the following is a precursor of both gonadal and adrenocortical hormones? 
Select and explain. 
A. Progesterone, B. Cortisol, C. Testosterone, D. Corticosterone
A: Progesterone
Answer: A: Progesterone 
Explanation: None