The scrotum expands and contracts to keep testicles at constant temperature.

• A. Contracts to keep temperature constant
• B. Expands and contracts to keep testicles at constant temperature
• C. Produces testosterone
• D. Stores developed sperm

Answer: (B)

Thermoregulation of the testes is the key idea. The scrotum can expand or contract through the action of muscles like the dartos and cremaster, which move the testes closer to or farther from the body. When temperatures are warm, these muscles relax and the scrotum allows the testes to hang away from the body to dissipate heat. When cooler, they contract to pull the testes in closer, helping maintain a temperature slightly cooler than the rest of the body, which is important for sperm production. The scrotum doesn’t produce testosterone—that happens in the testes’ Leydig cells—and it doesn’t store developed sperm—that occurs in the epididymis. So expanding and contracting to regulate temperature best describes its role.