Assertion `:-` Uricotelism is terrestrial adaptation.
Reason `:-` Uric acid is least toxic and can be removed with a minimum loss of water.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion .
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding Uricotelism**:
- Uricotelism refers to the excretion of uric acid as the primary nitrogenous waste product. Organisms that exhibit this type of excretion are known as uricotelic organisms.

2. **Identifying the Context**:
- Uric acid is one of the three main forms of nitrogenous waste, alongside ammonia and urea. Each of these forms has different levels of toxicity and water requirements for excretion.

3. **Comparing Toxicity Levels**:
- Among the three nitrogenous wastes:
- Ammonia is the most toxic and requires a large amount of water for safe excretion, making it suitable for aquatic organisms.
- Urea is less toxic than ammonia and requires less water for excretion, thus it is common in terrestrial animals.
- Uric acid is the least toxic and can be excreted with minimal water loss, making it advantageous for terrestrial organisms that need to conserve water.

4. **Relating Uric Acid to Terrestrial Adaptation**:
- Since uric acid can be excreted with minimal water loss, it is an effective adaptation for life on land, where water conservation is crucial. This supports the assertion that uricotelism is a terrestrial adaptation.

5. **Evaluating the Reason**:
- The reason states that uric acid is least toxic and can be removed with a minimum loss of water. This is true and directly supports the assertion that uricotelism is a terrestrial adaptation.

6. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation for the assertion.