Source of protons necessary for the reduction of `NADP^(+)` is

Options

A. `H_(2)O` which undergoes oxidation
B. ` PQH_(2)` which undergoes oxidation
C. `H^(+)` picked up by `PQ^(-)`
D. ` H^(+)` pool of stroma

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the source of protons necessary for the reduction of NADP⁺ during photosynthesis.

2. **Photosynthesis Overview**: In photosynthesis, particularly during the light-dependent reactions, water (H₂O) is split in a process known as photolysis. This process generates protons (H⁺), electrons, and oxygen.

3. **Photolysis of Water**: The reaction can be summarized as:
\[ 2H_2O \rightarrow 4H^+ + 4e^- + O_2 \]
Here, water is oxidized, releasing protons (H⁺) and electrons (e⁻).

4. **Role of Protons in NADP⁺ Reduction**: The protons (H⁺) produced from the photolysis of water are essential for the reduction of NADP⁺ to NADPH. This reduction occurs in the presence of electrons that are transferred through the electron transport chain.

5. **Conclusion**: Therefore, the source of protons necessary for the reduction of NADP⁺ is water (H₂O), which undergoes oxidation during the light reactions of photosynthesis.

### Final Answer:
The source of protons necessary for the reduction of NADP⁺ is **H₂O (water)**, which undergoes oxidation.

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