In calvin cycle, the reduction stage involves.

Options

A. Utilisation of 2 molecules of ATP for phosphorylation
B. Utilisation of 2 molecules of NADPH for reduction per `CO_(2)` molecule fixed
C. Utilisation of 12 molecules of NADPH for reduction of six molecules of `CO_(2)`
D. All of the above

Answer

### Step-by-Step Solution:

1. **Understanding the Calvin Cycle**: The Calvin Cycle, also known as the light-independent reactions or dark reactions, is a crucial part of photosynthesis where carbon dioxide is fixed into organic molecules.

2. **Identifying the Reduction Stage**: The reduction stage of the Calvin Cycle specifically refers to the phase where 3-phosphoglycerate (3-PGA) is converted into glyceraldehyde-3-phosphate (G3P). This stage is essential for synthesizing carbohydrates.

3. **Key Reactions in the Reduction Stage**:
- The process begins with 3-phosphoglycerate (3-PGA).
- ATP is utilized to phosphorylate 3-PGA, converting it into 1,3-bisphosphoglycerate (1,3-BPG).
- Next, 1,3-BPG is reduced to glyceraldehyde-3-phosphate (G3P) using NADPH.

4. **Energy Molecules Involved**:
- During this reduction stage, two molecules of ATP are consumed, which are converted into ADP.
- Additionally, two molecules of NADPH are used to reduce the 1,3-BPG to G3P, resulting in the formation of NADP+.

5. **Summary of the Reduction Stage**:
- The reduction stage involves the conversion of 3-PGA to G3P.
- It requires the utilization of 2 ATP and 2 NADPH per CO2 molecule fixed.
- The overall reaction leads to the production of G3P, which can be further utilized to form glucose and other carbohydrates.

### Final Answer:
The reduction stage of the Calvin Cycle involves the conversion of 3-phosphoglycerate (3-PGA) to glyceraldehyde-3-phosphate (G3P) using 2 ATP and 2 NADPH for every CO2 molecule fixed.

---