During light reaction in photosynthesis the following are formed.

Options

A. ATP and sugar
B. Hydrogen, `O_2` and sugar
C. ATP , hydogen donor and `O_2`
D. ATP , hydrogen and `O_2` donor

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**: Photosynthesis consists of two main stages: the light reactions and the dark reactions (Calvin cycle). The light reactions occur in the thylakoid membranes of chloroplasts and require light energy.

2. **Components of Light Reactions**: The light reactions involve chlorophyll, sunlight, water (H2O), and various electron transport chain components. The primary products of the light reactions are ATP, NADPH, and oxygen (O2).

3. **Photolysis of Water**: During the light reactions, water molecules are split in a process known as photolysis. This reaction produces oxygen gas (O2), protons (H+), and electrons (e-). The chemical equation for photolysis can be represented as:
\[ 2H_2O \rightarrow 4H^+ + 4e^- + O_2 \]

4. **Formation of ATP and NADPH**: The electrons released from the photolysis of water are transferred through the electron transport chain, which helps in the formation of ATP through chemiosmosis. The protons (H+) contribute to the proton gradient used to synthesize ATP.

5. **Identifying the Products**: From the above processes, we can summarize the main products formed during the light reactions:
- ATP (adenosine triphosphate)
- NADPH (nicotinamide adenine dinucleotide phosphate)
- O2 (oxygen gas)

6. **Analyzing the Options**: Now, we need to analyze the provided options:
- **Option A**: ATP and sugar - Incorrect, as sugar is produced in the dark reactions.
- **Option B**: Hydrogen, O2, and sugar - Incorrect, as sugar is not produced in light reactions.
- **Option C**: ATP, hydrogen donor, and O2 - Correct, as ATP and O2 are produced, and hydrogen is involved in the process.
- **Option D**: Hydrogen and O2 donor - Incorrect, as this does not accurately represent the products of light reactions.

7. **Conclusion**: Based on the analysis, the correct answer is **Option C**: ATP, hydrogen donor, and O2.

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