Assertion : Tubular secretion is more important in marine fishes and desert amphibians.
Reason : In marine fishes and desert amphibians, nephrons are aglomerular.

Options

A. If both Assertion and Reason are true and Reason is correct explanation of the Assertion.
B. If both Assertion and Reason are true but Reason is not correct explanation of the Assertion.
C. If Assertion is true but Reason is false.
D. If both Assertion and Reason are false.

Answer

To solve the question, we need to analyze the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Tubular secretion is more important in marine fishes and desert amphibians."
- Tubular secretion is a process where substances are actively transported from the blood into the renal tubules. In marine fishes and desert amphibians, this process is crucial for maintaining osmotic balance and excreting waste efficiently.

2. **Understanding the Reason**:
- The reason states that "In marine fishes and desert amphibians, nephrons are aglomerular."
- Aglomerular nephrons lack glomeruli, which are the structures responsible for filtering blood in the kidneys. This means that these organisms rely more on tubular secretion for waste removal since they do not have the filtration process that occurs in glomerular nephrons.

3. **Analyzing the Relationship**:
- The assertion is true because tubular secretion is indeed more important for marine fishes and desert amphibians due to their unique adaptations to conserve water and excrete waste.
- The reason is also true because the absence of glomeruli in these organisms' nephrons necessitates a greater reliance on tubular secretion for excretion.

4. **Determining the Correct Option**:
- Since both the assertion and the reason are true, and the reason correctly explains why tubular secretion is more important in these organisms, we conclude that the first option is correct: "Both reason and assertion are true, and reason is a correct explanation of assertion."

### Final Answer:
Both assertion and reason are true, and the reason is a correct explanation of the assertion.

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