Final answer:
The final vessel through which semen passes before being expelled from the body is the penile urethra.
Step-by-step explanation:
The final vessel through which semen must pass before being expelled from the body is the penile urethra. The path of semen begins in the testes and moves through the vas deferens.
The vas deferens carries sperm to the ejaculatory ducts, which are formed where the vas deferens join with the ducts of the seminal vesicles. Here, the sperm is mixed with secretions from the seminal vesicles and the prostate gland to form semen. Lastly, the semen is transported through the penile urethra during ejaculation. Therefore, the correct answer to the question is B) penile urethra.