Why should the ureter be less robust than the vas deferens

The vas deferens, also called ductus deferens, is part of the male reproductive system of many vertebrates; these ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. It is a partially coiled tube which exits the abdominal cavity through the inguinal canal.

Explanation:

answer; ///i believe that the correct answer is (a) specialized cells)

the sphincter muscles at the end of the digestive tract is the anus.