radial vascular bundles are those in which

Options

A. xylem is surrounded by phloem
B. phloem is surrounded by xylem
C. xylem and phloem occur on the same radius
D. xylem and phloem are found pm different radii.

Answer

To answer the question "Radial vascular bundles are those in which:", we will analyze the options provided and identify the correct one based on the definitions of different vascular bundle arrangements.

### Step-by-Step Solution:

1. **Understand Vascular Bundles**: Vascular bundles in plants consist of two main types of tissues: xylem and phloem. Xylem is primarily responsible for the transport of water and minerals, while phloem transports food.

2. **Identify the Types of Arrangements**:
- **Heterocentric**: This arrangement has xylem surrounded by phloem.
- **Leptocentric**: In this arrangement, phloem is surrounded by xylem.
- **Collateral**: Here, xylem and phloem occur on the same radius.
- **Radial**: In this arrangement, xylem and phloem are found on different radii.

3. **Focus on the Question**: The question specifically asks about radial vascular bundles.

4. **Define Radial Arrangement**: In a radial vascular bundle, the xylem and phloem are located at different radii from the center of the bundle. This means that they do not share the same radius but are instead positioned separately.

5. **Select the Correct Option**: Based on the definitions:
- The correct answer is that in radial vascular bundles, xylem and phloem are found on different radii.

### Final Answer:
Radial vascular bundles are those in which xylem and phloem are found in different radii.