Q. `Mn, Ca` and `Cl` present in PS II play an important role in

Options

A. a) Absorption of light
B. b) `CO_(2)` assimilation
C. c) Photolysis of water
D. d) ATP synthesis.

Answer

To answer the question regarding the role of Mn (Manganese), Ca (Calcium), and Cl (Chlorine) in Photosystem II, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photosystem II**: Photosystem II (PS II) is a crucial component of the light-dependent reactions of photosynthesis. It is responsible for capturing light energy and initiating the process of converting that energy into chemical energy.

2. **Role of Manganese, Calcium, and Chlorine**: In PS II, these three elements play a vital role in the process of photolysis of water. Photolysis refers to the splitting of water molecules into oxygen, protons, and electrons under the influence of light.

3. **Mechanism of Photolysis**: When light is absorbed by PS II, it energizes electrons, which then participate in a series of reactions. The splitting of water (H2O) occurs, producing oxygen (O2), protons (H+), and electrons (e-). The electrons replace those lost by chlorophyll in PS II.

4. **Specific Functions of Each Element**:
- **Manganese (Mn)**: It is part of the oxygen-evolving complex (OEC) in PS II, which is essential for the photolysis of water.
- **Calcium (Ca)**: It stabilizes the structure of the OEC and is involved in the regulation of the electron transport chain.
- **Chlorine (Cl)**: It is involved in maintaining the overall structure and function of the chlorophyll molecule and the OEC.

5. **Conclusion**: The primary role of Mn, Ca, and Cl in Photosystem II is to facilitate the photolysis of water, which is essential for the continuous supply of electrons needed for the light reactions of photosynthesis.

### Final Answer:
The correct option is **C. photolysis of water**.