Final answer:
The epididymis is a tightly coiled tubular structure that would be around 6 meters long if uncoiled, and it is responsible for the sperm maturation and storage, located atop the testes within the scrotum.
Step-by-step explanation:
The epididymis is a coiled tubular structure that plays a crucial role in the male reproductive system. Contrary to the provided options, the epididymis is not a long, straight structure, nor is it located in the upper abdomen, about 10 feet in length, or shaped like a half-moon. Instead, the epididymis is tightly coiled and would be approximately 6 meters (about 20 feet) long if straightened out. It is located atop the testes within the scrotum. The epididymis is responsible for the maturation and storage of sperm until they leave the body during ejaculation.