Assertion: Presence of photorespiration is considered as a wasteful and energy consuming process in crop plants, ultimately leads to reduction in yield.
Reason: During `C_(3)` synthesis upto `50% CO_(2)` fixed may have to pass through photorespiratory process to form carbohydrate such as sucrose.

Options

A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
C. Assertion is true but Reason is false
D. Both Assertion and Reason are false

Answer

To solve the question, we need to evaluate both the assertion and the reason provided and determine their validity and relationship.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that photorespiration is a wasteful and energy-consuming process in crop plants, which ultimately leads to a reduction in yield.
- **Evaluation**: This is true. Photorespiration occurs in C3 plants when the enzyme RuBisCO reacts with oxygen instead of carbon dioxide, leading to the production of a two-carbon compound instead of the typical three-carbon compound from photosynthesis. This process consumes energy and reduces the overall efficiency of photosynthesis, thereby lowering crop yield.

2. **Understanding the Reason**:
- The reason states that during C3 synthesis, up to 50% of the fixed CO2 may pass through the photorespiratory process to form carbohydrates such as sucrose.
- **Evaluation**: This statement is also true. In C3 plants, under certain conditions (like high oxygen concentration and low carbon dioxide concentration), a significant amount of fixed carbon can indeed be diverted into the photorespiratory pathway, which can account for a substantial portion of the carbon fixation process.

3. **Relationship Between Assertion and Reason**:
- The assertion claims that photorespiration is wasteful and reduces yield, while the reason explains a mechanism by which this occurs (i.e., the diversion of fixed CO2 into photorespiration).
- **Evaluation**: The reason provides a valid explanation for the assertion. If a large amount of CO2 is being diverted into a process that does not contribute to carbohydrate synthesis effectively, it supports the claim that photorespiration is wasteful and reduces yield.

4. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Final Answer:
Both assertion and reason are true, and reason is the correct explanation of assertion.