Photosystem `II` is concerned with

Options

A. Photolysis of water
B. Flowering
C. Reduction of `CO_(2)`
D. Release of energy.

Answer

### Step-by-Step Solution:

1. **Understanding Photosystem II**: Photosystem II (PSII) is a crucial component of the photosynthetic process in plants. It is primarily involved in the light-dependent reactions of photosynthesis.

2. **Identifying the Reaction Center**: The reaction center of Photosystem II is known as P680. This is where the light energy is absorbed and converted into chemical energy.

3. **Role of Water in Photosystem II**: One of the key functions of Photosystem II is the photolysis of water. This process involves the splitting of water molecules into oxygen, protons, and electrons.

4. **Mechanism of Photolysis**: When light energy is absorbed by P680, it excites electrons, which are then transferred through a series of proteins in the thylakoid membrane. To replace the lost electrons, water molecules are split (photolysis), and this process releases oxygen as a byproduct.

5. **Conclusion**: Based on the above points, we can conclude that Photosystem II is primarily concerned with the photolysis of water.

6. **Final Answer**: Therefore, the correct answer to the question is that Photosystem II is concerned with the **photolysis of water**.