A: The first step towards photosynthesis is reduction of `CO_2`.
R:ATP is released by the reduction of `CO_2`.

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the assertion and reason question regarding photosynthesis, we will analyze both statements step by step.

### Step 1: Understand the Assertion
- **Assertion (A)**: "The first step towards photosynthesis is the reduction of CO₂."
- In photosynthesis, the process begins with the fixation of carbon dioxide (CO₂) during the Calvin cycle (also known as the dark reaction). The first stable product formed is 3-phosphoglycerate (3-PGA) after CO₂ combines with ribulose bisphosphate (RuBP). This indicates that the assertion is correct because the reduction of CO₂ is indeed a key step in photosynthesis.

### Step 2: Understand the Reason
- **Reason (R)**: "ATP is released by the reduction of CO₂."
- During the Calvin cycle, ATP is used (not released) to convert 3-PGA into glyceraldehyde-3-phosphate (G3P). The energy for this process comes from the ATP produced during the light-dependent reactions of photosynthesis. Therefore, this statement is incorrect because the process consumes ATP rather than releasing it.

### Step 3: Conclusion
- Based on the analysis:
- The assertion (A) is true.
- The reason (R) is false.

Thus, the correct conclusion is that A is correct, and R is incorrect.

### Final Answer
- The correct answer is that the assertion is true, but the reason is false.

---