Find the odd one (w.r.t double carboxylation).

Options

A. Zea mays
B. sugarcane
C. Pisum sativum
D. Sorghum

Answer

To solve the question "Find the odd one (w.r.t double carboxylation)", we will analyze the given options based on their classification as C3 or C4 plants, since double carboxylation is a characteristic of C4 plants.

### Step-by-Step Solution:

1. **Understand Double Carboxylation**:
- Double carboxylation refers to the process of carbon dioxide fixation that occurs twice in C4 plants. The first fixation occurs in the mesophyll cells, and the second fixation occurs in the bundle sheath cells.

2. **Identify the Options**:
- The options provided are:
1. GMA (Giant Maize)
2. Sugarcane
3. Pythium stibium
4. Sorghum

3. **Classify Each Option**:
- **Giant Maize (GMA)**: This is a C4 plant.
- **Sugarcane**: This is also a C4 plant.
- **Pythium stibium**: This is a C3 plant.
- **Sorghum**: This is a C4 plant.

4. **Determine the Odd One Out**:
- C4 plants (Giant Maize, Sugarcane, and Sorghum) perform double carboxylation, while C3 plants (Pythium stibium) only perform single carboxylation.
- Therefore, Pythium stibium is the odd one out because it does not undergo double carboxylation.

5. **Conclusion**:
- The odd one out in the context of double carboxylation is **Pythium stibium**.

### Final Answer:
The odd one with respect to double carboxylation is **Pythium stibium**.