A zone of gradual change in temperature of a lake is

Options

A. Hypolimnion
B. Epilimnion
C. Thermocline
D. None of the above.

Answer

To answer the question "A zone of gradual change in temperature of a lake is," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Layers of a Stratified Lake**:
- Lakes are often stratified into different layers based on temperature and density. The three main layers are:
- **Epilimnion**: The upper layer of warm water.
- **Metalimnion (Thermocline)**: The middle layer where temperature changes rapidly.
- **Hypolimnion**: The bottom layer of cooler water.

2. **Identify the Correct Term**:
- The question specifically asks for the zone of gradual change in temperature. This is characterized by a rapid transition from warmer to cooler water.
- The term that describes this zone is **thermocline**.

3. **Eliminate Incorrect Options**:
- **Epilimnion**: This is the warm upper layer, not a zone of gradual change.
- **Hypolimnion**: This is the cold bottom layer, also not a zone of gradual change.
- Therefore, the only correct answer is **thermocline**.

4. **Conclusion**:
- The zone of gradual change in temperature of a lake is known as the **thermocline**.

### Final Answer:
The correct option is **thermocline**.

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