Select the MISMATCHED pair out of the following.

Options

A. Radial vascular bundle - xylem and phloem on different radii
B. Bicollateral vascular bundle - phloem present on the both side of xylem
C. Open vascular bundle - phloem surrounds xylem
D. Conjoint vascular bundle - xylem and phloem on same radii

Answer

To solve the question of selecting the mismatched pair from the given options regarding vascular bundles, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the First Option: Radial Vascular Bundle**
- The statement given is that xylem and phloem are on different radii.
- **Analysis**: This is a correct description of a radial vascular bundle. In this type, xylem and phloem are indeed located on different radii.
- **Conclusion**: This pair is correctly matched.

2. **Identify the Second Option: Collateral Vascular Bundle**
- The statement given is that phloem is present on both sides of xylem.
- **Analysis**: This description is accurate for a bicollateral vascular bundle, where phloem is found on both sides of the xylem.
- **Conclusion**: This pair is also correctly matched.

3. **Identify the Third Option: Upper Vascular Bundle**
- The statement given is that phloem surrounds the xylem.
- **Analysis**: This description is incorrect. In a typical vascular bundle, xylem is surrounded by phloem, not the other way around. The cambium is usually present between xylem and phloem.
- **Conclusion**: This pair is mismatched.

4. **Identify the Fourth Option: Conjoined Vascular Bundles**
- The statement given is that xylem and phloem are on the same radii.
- **Analysis**: This is a correct description of conjoined vascular bundles, where xylem and phloem are indeed located on the same radius.
- **Conclusion**: This pair is correctly matched.

### Final Answer:
The mismatched pair is **Option 3: Upper Vascular Bundle** (phloem surrounds xylem).