ring bark occurs in

Options

A. psidium
B. eucalyptus
C. acacia
D. all the above.

Answer

**Step-by-Step Solution:**

1. **Understanding Bark**: Begin by defining what bark is. Bark is the outermost layer of stems and roots of woody plants, which includes trees, woody vines, and shrubs. It encompasses all the tissues outside the vascular cambium.

2. **Identifying the Types of Bark**: Recognize that there are different types of bark present in various plants. For example, some plants have scaly bark, while others may have ring-type bark.

3. **Analyzing the Options**:
- **Obsidian**: This is not a plant; it is a volcanic glass, so it cannot be the correct answer.
- **Eucalyptus**: This plant is known to exhibit ring bark, which is a specific type of bark formation.
- **Acacia**: In this case, the bark is either absent or not present, which means it does not exhibit ring bark.
- **All of the above**: Since not all the options exhibit ring bark, this cannot be the correct answer.

4. **Conclusion**: Based on the analysis, the only plant that exhibits ring bark is eucalyptus. Therefore, the correct answer is eucalyptus.

**Final Answer**: Eucalyptus

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