Which of the following absorb light energy for photosynthesis : -

Options

A. Chlorophyll
B. Water molecule
C. `O_(2)`
D. RuBP

Explanation

To determine which of the following absorb light energy for photosynthesis, we can analyze each option provided:

1. **Chlorophyll**: Chlorophyll is the primary pigment involved in photosynthesis. It is located in the chloroplasts of plant cells and is responsible for absorbing light energy, particularly in the blue and red wavelengths of light. Chlorophyll reflects green light, which is why plants appear green. Therefore, chlorophyll is essential for capturing light energy for photosynthesis.

2. **Water Molecule**: Water is a crucial component of photosynthesis, but it does not absorb light energy. Instead, it acts as a reactant in the process, providing electrons and protons during the light-dependent reactions. Water is split (photolysis) to release oxygen, but it does not absorb light energy itself.

3. **Oxygen**: Oxygen is a byproduct of photosynthesis and is released into the atmosphere. It is not involved in absorbing light energy; rather, it is produced when water is split during the light reactions of photosynthesis.

4. **RuBP (Ribulose bisphosphate)**: RuBP is a five-carbon sugar that plays a role in the Calvin cycle of photosynthesis. It is involved in the fixation of carbon dioxide but does not absorb light energy. Its primary function is to combine with carbon dioxide to eventually produce glucose.

Based on this analysis, the only option that absorbs light energy for photosynthesis is **Chlorophyll**.

### Final Answer:
The correct option is **Chlorophyll**.