Bark refers to

Options

A. (a) phellem + phellogen + phelloderm
B. (b) periderm + cortex
C. (c) phellem + phelloderm + secondary phloem
D. (d) periderm + cortex + pericycle + secondary phloem

Explanation

**Step-by-Step Solution:**

1. **Understanding Bark**: Bark is a term used to describe the outer protective layer of a tree. It encompasses various tissues that are located outside the vascular cambium.

2. **Characteristics of Bark**: Bark can vary in color from light to dark brown. It serves several important functions, including acting as a heat screen, being insect-repellent, and providing resistance to decay and fire.

3. **Composition of Bark**: Bark is primarily made up of different layers. It is divided into two main parts: the inner bark and the outer bark.

4. **Inner Bark**: The inner bark consists of living tissues, including:
- **Periderm**: This is the outermost layer of the inner bark, providing protection.
- **Cortex**: This layer stores food and provides structural support.
- **Pericycle**: This layer is involved in the formation of lateral roots.
- **Secondary Phloem**: This tissue is responsible for transporting nutrients.

5. **Outer Bark**: The outer bark is primarily composed of dead cells and serves as the protective layer of the tree.

6. **Conclusion**: Based on the composition of bark, the correct answer to the question "Bark refers to" is that it constitutes Periderm, Cortex, Pericycle, and Secondary Phloem.

**Final Answer**: Bark refers to Periderm, Cortex, Pericycle, and Secondary Phloem (Option D).

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