What causes the penis to develop?
Options:
- (A) Creatine
- (B) Energy
- (C) Estrogen
- (D) Testicles
- (E) matter vibrating
- (F) Testosterone
- (G) movement
- (H) It expands OK. Let's think hard:
Testosterone stimulates the reproductive organs to develop into male organs. Male mammals have a tube-like organ called the 'penis'. Testosterone causes the penis to develop.
So, the final answer is (F).