[A]: Oxidation of `H_2O` takes place during pho- tosynthesis.
[R]: Photosynthesis is an oxidation-reduction process where `H_2O` is oxidised to `O_2` and `CO_2` is reduced to `(CH_2O)_(n)` ·

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

**Step-by-Step Solution:**

1. **Understanding Photosynthesis**: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. This process primarily occurs in the chloroplasts of plant cells.

2. **Identifying the Components**: The main components involved in photosynthesis are:
- Water (`H2O`)
- Carbon dioxide (`CO2`)
- Chlorophyll (the pigment that captures sunlight)
- Sunlight (the energy source)

3. **Oxidation of Water**: During the light-dependent reactions of photosynthesis, water molecules are split (a process called photolysis) to release oxygen (`O2`). In this reaction, water is oxidized, meaning it loses electrons.

4. **Reduction of Carbon Dioxide**: In the light-independent reactions (Calvin Cycle), carbon dioxide is reduced to form glucose. This means that carbon dioxide gains electrons to form a carbohydrate (sugar) molecule, represented as `(CH2O)n`.

5. **Redox Process**: Photosynthesis is an example of a redox (oxidation-reduction) process. In this process, oxidation (loss of electrons) and reduction (gain of electrons) occur simultaneously:
- Water is oxidized to oxygen.
- Carbon dioxide is reduced to glucose.

6. **Conclusion**: Both the assertion and reason provided in the question are true. The oxidation of water does take place during photosynthesis, and it is indeed an oxidation-reduction process where water is oxidized to oxygen and carbon dioxide is reduced to sugar.

**Final Statement**: Therefore, both the assertion [A] and the reason [R] are true, and the reason [R] correctly explains the assertion [A].

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