In mammals, the testes occur in scrotal sacs outside the viscera because of the

Options

A. Presence of urinary bladder
B. Presence of rectum
C. Long vas defrens
D. Requirement of low temperature for spermatogenesis.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks why the testes in mammals are located in scrotal sacs outside the body cavity (viscera).

2. **Identifying the Options**: The options given are:
- A) Presence of urinary bladder
- B) Presence of rectum
- C) Long vas deferens
- D) Requirement of low temperature for spermatogenesis

3. **Analyzing the Function of Testes**: The primary function of the testes is to produce sperm through a process called spermatogenesis.

4. **Temperature Requirement for Spermatogenesis**: Spermatogenesis requires a temperature that is lower than the normal body temperature. The ideal temperature for sperm production is about 2-3 degrees Celsius lower than the body temperature.

5. **Role of Scrotal Sacs**: The scrotal sacs provide an external environment that helps maintain this lower temperature, which is crucial for the proper development of sperm.

6. **Conclusion**: Based on the analysis, the correct reason for the location of the testes in scrotal sacs is the requirement of low temperature for spermatogenesis.

7. **Final Answer**: Therefore, the answer to the question is option D: requirement of low temperature for spermatogenesis.

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