Which of the following conditions shows the effect of photo-stratification?

Options

A. Profundal zone has both heterotrophs and phytoplanktons.
B. Profundal zone harbors only heterotrophs.
C. Planktons are only found in littoral zone.
D. Heterotrophs are maximum in limnetic zone.

Answer

To solve the question regarding which condition shows the effect of photo-stratification, we will analyze the different zones of a lake and their characteristics:

### Step-by-Step Solution:

1. **Understand Photo-Stratification**:
- Photo-stratification refers to the layering of water in a lake based on the penetration of sunlight. This leads to different ecological zones with distinct characteristics.

2. **Identify the Zones**:
- **Littoral Zone**: This is the shallow area near the shore where sunlight penetrates fully. It supports a variety of aquatic plants and phytoplankton due to abundant light.
- **Limnetic Zone**: This is the open water area where sunlight can penetrate to a certain depth. It also supports phytoplankton, but not as much as the littoral zone.
- **Profundal Zone**: This is the deep water area where sunlight does not penetrate at all. It is characterized by a lack of light, leading to the absence of photosynthetic organisms like phytoplankton.

3. **Analyze the Options**:
- The question asks which condition shows the effect of photo-stratification. The key is to identify which zone is characterized by the absence of light and supports heterotrophic organisms.
- The **Profundal Zone** is where there is no light, and thus it does not support phytoplankton (which are autotrophs). Instead, it harbors heterotrophic organisms that rely on organic matter.

4. **Conclusion**:
- Based on the analysis, the correct answer is that the **Profundal Zone** shows the effect of photo-stratification as it is characterized by zero light conditions and is primarily inhabited by heterotrophs.

### Final Answer:
The condition that shows the effect of photo-stratification is the **Profundal Zone**.

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