Final answer:
The ductus deferens is medial to the entrance of the ureter into the bladder because the ductus deferens ends posterior to the bladder, while the ureters enter the bladder wall obliquely from a medial direction.
Step-by-step explanation:
The ureters collect urine from the kidneys and transport it to the urinary bladder. The path of the ureters includes passing laterally as they enter the pelvic region, but as they approach the bladder, they turn medially and enter the bladder wall obliquely. This oblique insertion creates a one-way valve to prevent urine from flowing back into the ureters from the bladder.
The ductus deferens (also known as the vas deferens) is part of the male reproductive system and carries sperm from the epididymis through the inguinal canal into the pelvic cavity, ending posterior to the bladder where it enlarges to form the ampulla. Given the positioning of the ductus deferens and the pathway of the ureters as they enter the bladder, we can determine that the ductus deferens is medial to the entrance of the ureter into the bladder.
Therefore, the correct answer to the question is: B) Medial