In human males, what organ of the excretory system merges with the vas deferens of the reproductive tract?

The urethra is the correct answer because it serves as the duct through which both urine and semen are expelled from the body in human males. The vas deferens, which transports sperm from the testes, merges with the urethra at the point where semen is discharged during ejaculation. This dual function is unique to males, as the urethra is part of both the excretory and reproductive systems.

The bladder, while part of the excretory system where urine is stored, does not merge with the vas deferens; it functions separately to collect urine before it is expelled through the urethra. The prostate gland produces fluid that nourishes and transports sperm, but it is not the organ that merges with the vas deferens. The kidneys are involved in filtering blood and producing urine but do not have a direct connection to the vas deferens or the reproductive tract.