`ATP` formation during photosynthesis is

Options

A. Phosphorylation
B. Photophosphorylation
C. Oxidative phosphorylation
D. None of the above.

Answer

### Step-by-Step Solution:

1. **Understanding ATP Formation**: ATP (adenosine triphosphate) is the energy currency of the cell. Its formation is crucial during various biological processes, including photosynthesis.

2. **Identifying the Options**: The question provides several options for ATP formation during photosynthesis:
- Phosphorylation
- Photophosphorylation
- Oxidative phosphorylation

3. **Evaluating Phosphorylation**:
- Phosphorylation generally refers to the addition of a phosphate group to an organic molecule.
- While it does involve the conversion of ADP (adenosine diphosphate) and inorganic phosphate into ATP, this process is not specifically associated with photosynthesis.
- **Conclusion**: This option is incorrect.

4. **Evaluating Photophosphorylation**:
- Photophosphorylation is the process where light energy is used to convert ADP and inorganic phosphate into ATP.
- This process occurs during the light-dependent reactions of photosynthesis, where chlorophyll absorbs sunlight and converts it into chemical energy.
- **Conclusion**: This option is correct.

5. **Evaluating Oxidative Phosphorylation**:
- Oxidative phosphorylation is a process that occurs during cellular respiration, specifically in aerobic organisms.
- It involves the production of ATP through the electron transport chain and chemiosmosis, but it is not part of photosynthesis.
- **Conclusion**: This option is incorrect.

6. **Final Answer**: Based on the evaluations, the correct answer to the question "ATP formation during photosynthesis is" is **Photophosphorylation**.