Products of light reaction are

Options

A. `O_2` and `CO_2`
B. `CO_2` and `H_2O`
C. ATP and NADPH
D. ATP and `CO_2`

Answer

To answer the question about the products of the light reaction in photosynthesis, we can break down the process into clear steps:

### Step-by-Step Solution:

1. **Understanding Light Reactions**:
- Light reactions occur in the thylakoid membranes of chloroplasts during photosynthesis. They convert light energy into chemical energy.

**Hint**: Remember that light reactions are the first stage of photosynthesis and involve capturing sunlight.

2. **Types of Photophosphorylation**:
- There are two types of photophosphorylation: cyclic and non-cyclic.
- **Cyclic Photophosphorylation**: In this process, only ATP is produced.
- **Non-Cyclic Photophosphorylation**: This process produces ATP, NADPH, and oxygen as a by-product.

**Hint**: Differentiate between cyclic and non-cyclic processes based on their products.

3. **Products of Non-Cyclic Photophosphorylation**:
- The main products are ATP and NADPH, which are used in the Calvin cycle for synthesizing glucose.
- Oxygen is released as a by-product during this process.

**Hint**: Focus on the fact that oxygen is a by-product, not a main product.

4. **Products of Cyclic Photophosphorylation**:
- The only product here is ATP, which is generated when electrons cycle back to the photosystem.

**Hint**: Cyclic photophosphorylation is simpler and only yields ATP.

5. **Evaluating Options**:
- Option A: Oxygen and carbon dioxide - Incorrect (carbon dioxide is not a product of light reactions).
- Option B: Carbon dioxide and water - Incorrect (neither is produced in light reactions).
- Option C: ATP and NADPH - Correct (produced in non-cyclic photophosphorylation).
- Option D: ATP and carbon dioxide - Incorrect (carbon dioxide is not produced).

**Hint**: Cross-check each option against the known products of light reactions.

### Final Answer:
The products of the light reaction are ATP and NADPH, with oxygen being a by-product. Therefore, the correct option is **Option C**.