Answer:
D.  
Explanation:
The highlighted part of the male reproductive system is the urethra.
One of its major functions is to serve as a conduit for semen and sperm during sexual acts.
A is wrong. The testes manufacture sperm cells.
B is wrong. The prostate gland, the seminal vesicles, and the bulbourethral glands create the fluid in semen.
C is wrong. The epididymis stores sperm cells until they mature.