Assertion : The aquatic organisms in which the osmotic concentration and temperature of body change according to the ambient conditions of water are referred to as conformers.
Reason : Aquatic organisms are able to maintain homeostsis through thrmoregulation and osmoregulation by physiological or behavioural means.

Explanation

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

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that aquatic organisms, whose osmotic concentration and body temperature change according to the ambient conditions of water, are referred to as conformers.
- This statement is true. Conformers are organisms that do not have the ability to regulate their internal environment and instead adjust to the external conditions.

2. **Understanding the Reason**:
- The reason states that aquatic organisms are able to maintain homeostasis through thermoregulation and osmoregulation by physiological or behavioral means.
- This statement is false for conformers. Conformers do not maintain homeostasis; they change their internal conditions to match the external environment and do not have mechanisms for thermoregulation or osmoregulation.

3. **Conclusion**:
- Since the assertion is true and the reason is false, we conclude that the correct answer is that the assertion is true, but the reason is false.

### Final Answer:
- The assertion is true, and the reason is false.