Hypolimnion of a deep lake

Options

A. Freees during cold winter
B. Warms up during hot summer
C. Remains cool throughout
D. Remins warm throughout.

Answer

### Step-by-Step Solution:

1. **Understanding Hypolimnion**:
- The hypolimnion is the deepest layer of water in a stratified lake. It lies below the thermocline, which is the layer where the temperature changes rapidly with depth.

2. **Characteristics of Hypolimnion**:
- The hypolimnion is typically the coldest layer of the lake during the summer months. It remains at a relatively stable temperature, usually around 4 degrees Celsius.

3. **Behavior in Different Seasons**:
- In summer, the hypolimnion remains cool compared to the upper layers of the lake (epilimnion) which warm up due to sunlight.
- In winter, the hypolimnion can be warmer than the ice-covered surface, as water reaches its maximum density at 4 degrees Celsius.

4. **Evaluating the Options**:
- Option 1: "It freezes during the cold winter" - Incorrect, as the hypolimnion does not freeze.
- Option 2: "It warms up during hot summer" - Incorrect, as it remains cool.
- Option 3: "It remains cool throughout" - Correct, as it maintains a stable, cool temperature.
- Option 4: "It remains warm throughout" - Incorrect, as it is not warm.

5. **Conclusion**:
- Based on the characteristics and behavior of the hypolimnion, the correct answer is that it remains cool throughout the year.

### Final Answer:
**The hypolimnion of a deep lake remains cool throughout the year. (Option 3)**

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