Step 1: Understanding testis temperature regulation.
The testis needs to be kept at a temperature lower than the core body temperature for optimal sperm production. This is achieved by the scrotum, which hangs outside the body to provide a cooler environment.
Step 2: Analyzing the options.
(A) proximal tubule: Incorrect — The proximal tubule is part of the kidney, not involved in regulating testis temperature.
(B) loop of Henle: Incorrect — The loop of Henle is involved in kidney function, not temperature regulation of the testis.
(C) scrotum: Correct — The scrotum holds the testes outside the body, which helps in maintaining a lower temperature.
(D) seminal vesicles: Incorrect — Seminal vesicles produce seminal fluid, not involved in temperature regulation of the testes.
Step 3: Conclusion.
The correct answer is (C) scrotum.