Pneumatophores are useful in

Options

A. Respiration
B. Transpiration
C. Guttation
D. Protein synthesis.

Answer

### Step-by-Step Solution:

1. **Understanding Pneumatophores**:
- Pneumatophores are specialized root structures that are typically found in plants that grow in saline or marshy environments. They are adaptations that help these plants survive in conditions where the soil is often waterlogged and lacks oxygen.

2. **Function of Pneumatophores**:
- The primary function of pneumatophores is to facilitate respiration. They grow above the soil surface and have small pores (lenticels) that allow for gas exchange. This is crucial for the plant's survival as it helps in the uptake of oxygen from the atmosphere.

3. **Analyzing the Options**:
- **Option A: Respiration** - This is the correct answer, as pneumatophores primarily aid in the respiratory process.
- **Option B: Transpiration** - This is incorrect. Transpiration involves the loss of water vapor from the leaves through stomata, not through pneumatophores.
- **Option C: Guttation** - This is also incorrect. Guttation refers to the exudation of water droplets from the plant's leaves, which occurs through specialized structures called hydathodes.
- **Option D: Protein Synthesis** - This is incorrect as well. Protein synthesis is a biochemical process that occurs in cells, involving the formation of proteins from amino acids, and is not related to the function of pneumatophores.

4. **Conclusion**:
- Based on the above analysis, the correct answer is **Option A: Respiration**.