The absorption of radiant energy causes

Options

A. Reduction of chlorophyll
B. Oxidation of chlorophyll
C. Absorption of ` CO_(2)`
D. Oxidation of `CO_(2)`

Answer

### Step-by-Step Solution:

1. **Understanding Radiant Energy**: Radiant energy refers to the energy carried by electromagnetic waves, particularly in the form of light. In the context of photosynthesis, this energy is primarily derived from sunlight.

2. **Role of Light in Photosynthesis**: When sunlight (radiant energy) strikes the chlorophyll molecules in plants, it is absorbed by the light-harvesting complexes known as photosystems (Photosystem I and Photosystem II).

3. **Electron Ejection**: The absorption of light energy leads to the excitation of electrons in the chlorophyll molecules. This excitation causes electrons to be ejected from the reaction center of the photosystems.

4. **Oxidation of Chlorophyll**: The ejection of electrons results in a positive charge on the chlorophyll molecule, indicating that it has lost an electron. This process is known as oxidation. Therefore, the chlorophyll molecule is oxidized when it loses electrons due to the absorption of radiant energy.

5. **Water Splitting and Electron Replacement**: To replace the lost electrons, the water-splitting complex (oxygen-evolving complex) in Photosystem II breaks down water molecules, releasing oxygen and providing electrons to replenish the chlorophyll.

6. **Formation of NADPH**: The electrons that are ejected from both photosystems eventually travel through an electron transport chain and are used to reduce NADP+ to NADPH, which is essential for the Calvin cycle where carbon dioxide is fixed into organic compounds.

7. **Conclusion**: Based on the above steps, the correct answer to the question "The absorption of radiant energy causes" is the **oxidation of chlorophyll**.