In root-stem transition region the vascular bundles are

Options

A. radial
B. conjoint
C. collateral
D. none

Answer

To answer the question regarding the type of vascular bundles found in the root-stem transition region, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Transition Region**: The root-stem transition region is the area where the root connects to the stem. This region is crucial for the transport of nutrients and water from the roots to the stem.

2. **Identify Vascular Bundle Types**:
- **Radial Vascular Bundles**: Typically found in roots, where the xylem and phloem are arranged in separate groups.
- **Conjoined Collateral Vascular Bundles**: Commonly found in stems, where xylem and phloem are arranged together in a single bundle.

3. **Analyze the Vascular Bundles in the Transition Region**:
- In the transition region, the vascular bundles are undergoing changes as they shift from the radial arrangement of the root to the conjoined collateral arrangement of the stem.
- Since this region is a transitional phase, the vascular bundles do not fit neatly into either category.

4. **Conclusion**: Given that the vascular bundles in the transition region do not conform to the definitions of either radial or conjoined collateral, we conclude that they do not belong to any specific type of vascular bundle.

5. **Final Answer**: Therefore, the correct answer to the question is **none**.