Concentric vascular bundles are

Options

A. open
B. closed
C. may be open or closed
D. endarch

Answer

**Step-by-Step Solution:**

1. **Understanding Vascular Bundles**: Vascular bundles are structures in plants that contain the xylem and phloem, which are responsible for the transport of water, nutrients, and food.

2. **Types of Vascular Bundles**: There are different types of vascular bundles based on their arrangement and presence of cambium:
- **Open Vascular Bundles**: These have a layer of cambium between the xylem and phloem, allowing for secondary growth.
- **Closed Vascular Bundles**: These lack cambium and do not allow for secondary growth.

3. **Concentric Vascular Bundles**: In concentric vascular bundles, one type of vascular tissue surrounds the other. This means that either:
- The phloem surrounds the xylem, or
- The xylem surrounds the phloem.

4. **Nature of Concentric Vascular Bundles**: Concentric vascular bundles are always classified as closed because they do not have a cambium layer between the xylem and phloem. This means that secondary growth does not occur in these bundles.

5. **Conclusion**: Therefore, concentric vascular bundles are always closed.

**Final Answer**: Concentric vascular bundles are closed.

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