Assertion: Kidneys of the vertebrates are retroperitoneal and extracoelomic.
Reason: The structural and functional units of the kidneys are nephrons.

Options

A. (a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
B. (b) lf both Assertion and Reason are true, but the Reason is not the correct explanation of the Assertion.
C. (c) If Assertion is true, but Reason is false
D. (d) If both Assertion and Reason are false

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion:**
- The assertion states that "Kidneys of the vertebrates are retroperitoneal and extracoelomic."
- **Retroperitoneal** refers to the anatomical position of the kidneys, meaning they are located behind the peritoneum, which is the lining of the abdominal cavity.
- **Extracoelomic** indicates that the kidneys are situated outside the coelomic cavity, which is lined by mesoderm.

2. **Evaluating the Reason:**
- The reason states that "The structural and functional units of the kidneys are nephrons."
- Nephrons are indeed the basic structural and functional units of the kidneys, responsible for filtering blood and producing urine.

3. **Determining the Truth of Both Statements:**
- Both the assertion and the reason are true statements.
- The assertion correctly describes the anatomical position of the kidneys, while the reason accurately identifies nephrons as the functional units of the kidneys.

4. **Analyzing the Relationship Between Assertion and Reason:**
- While both statements are true, the reason does not explain the assertion.
- The position of the kidneys (retroperitoneal and extracoelomic) is unrelated to the function of nephrons.

5. **Conclusion:**
- Since both the assertion and reason are true, but the reason does not provide a correct explanation for the assertion, the correct answer is option B: "Both assertion and reason are true but reason is not the correct explanation of assertion."

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