Low -temperature sensitivity of `C_(4)` plants are due to
(a) PEP synthetase
(b) PEPCO
(c) RuBisCO
(d) Malate dehydrogenase

Options

A. PEP synthetase
B. PEPCO
C. RuBisCO
D. Malate dehydrogenase

Answer

To solve the question regarding the low-temperature sensitivity of C4 plants, we will analyze the options provided and determine which enzyme is responsible for this sensitivity.

### Step-by-Step Solution:

1. **Understanding C4 Plants**: C4 plants are known for their efficient photosynthesis mechanism, which allows them to thrive in high temperatures and intense sunlight. They have a unique pathway that helps them concentrate CO2, which is beneficial for photosynthesis.

2. **Identifying Low-Temperature Sensitivity**: The question specifically asks about the low-temperature sensitivity of C4 plants. This means we need to identify which enzyme's activity is affected by lower temperatures.

3. **Analyzing the Options**:
- **(a) PEP synthetase**: This enzyme plays a role in the C4 pathway by converting phosphoenolpyruvate (PEP) to oxaloacetate. It is sensitive to temperature changes.
- **(b) PEPCO**: Phosphoenolpyruvate carboxylase (PEPC) is crucial for the initial fixation of CO2 in C4 plants but is not primarily responsible for low-temperature sensitivity.
- **(c) RuBisCO**: Ribulose bisphosphate carboxylase/oxygenase (RuBisCO) is involved in the Calvin cycle, but it is more associated with C3 plants and does not directly relate to the low-temperature sensitivity of C4 plants.
- **(d) Malate dehydrogenase**: This enzyme is involved in the conversion of malate to oxaloacetate but is not the primary factor for low-temperature sensitivity.

4. **Conclusion**: Based on the analysis, the low-temperature sensitivity of C4 plants is primarily due to the presence of **PEP synthetase**. Therefore, the correct answer is **(a) PEP synthetase**.

### Final Answer:
The low-temperature sensitivity of C4 plants is due to **(a) PEP synthetase**.