Answer:
C. The testes
Step-by-step explanation:
The testes, also called testicles, are the only external male sex organs from the list of answers. They are in charge of producing sperm and testosterone. They actually need to be outside the body, to be just a tiny bit cooler than the main body core temperature in order to produce sperms, that's why they are placed in the scrotum pouch.
The prostate and Cowper glands are internal as well as the vas deferens which is a canal transporting the sperm.