Plants growing in different strata in a water body manage minimum their photosynthetic efficiency by

Options

A. Changing source of energy (chemical)
B. Adjusting pigment composition
C. Utilising only blue region of PAR
D. Producing more number of Chlorophyll a molecules

Answer

To solve the question regarding how plants growing in different strata of a water body manage their photosynthetic efficiency, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**:
- Plants in a water body grow in different layers or strata. Each stratum has varying light availability due to factors like depth and water clarity.

2. **Identifying Photosynthetic Efficiency**:
- Photosynthetic efficiency refers to how effectively plants convert light energy into chemical energy during photosynthesis. This efficiency can be influenced by light quality, intensity, and the pigments present in the plants.

3. **Analyzing the Options**:
- **Option A**: Changing source of energy, chemical, adjusting pigment composition.
- **Option B**: Utilizing only blue region of PAR (Photosynthetically Active Radiation).
- **Option C**: Reducing the number of chlorophyll molecules.

4. **Evaluating Each Option**:
- **Option A**: This suggests that plants can adjust their chemical energy sources and pigment composition to optimize photosynthesis. This is plausible since different pigments can absorb various wavelengths of light, which is crucial in low-light conditions.
- **Option B**: Utilizing only the blue region of PAR may not be efficient as plants also need other wavelengths for optimal photosynthesis.
- **Option C**: Reducing chlorophyll molecules would likely decrease photosynthetic efficiency, not enhance it.

5. **Conclusion**:
- The most logical option is **Option A**: changing the source of energy and adjusting pigment composition. This allows plants to adapt to their specific light conditions in different strata, maximizing their photosynthetic efficiency.

### Final Answer:
**Option A: Changing source of energy, chemical, adjusting pigment composition.**

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