Secondary medullary rays are

Options

A. Narrow band of parenchyma
B. Arranged transversely
C. Dead and lignified
D. Formed by primary cambium

Answer

To answer the question about secondary medullary rays, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Concept**: Secondary medullary rays are structures found in the secondary growth of plants, particularly in woody plants. They are important for the transport of nutrients and water.

2. **Formation**: Secondary medullary rays are formed from the cambium ring. The cambium is a layer of meristematic tissue that contributes to the secondary growth of stems and roots.

3. **Tissue Type**: The cells that make up the secondary medullary rays are primarily parenchyma cells. Parenchyma is a type of simple tissue that is involved in storage, photosynthesis, and tissue repair.

4. **Arrangement**: These parenchyma cells are arranged in narrow bands that run radially through the secondary xylem (wood) and phloem (bark) tissues.

5. **Characteristics**: The secondary medullary rays are not dead or lignified; they are living parenchyma cells that help in the radial transport of nutrients and water.

6. **Conclusion**: Based on the above points, the correct answer to the question "Secondary medullary rays are" is that they are a narrow band of parenchyma cells.

### Final Answer:
**Secondary medullary rays are a narrow band of parenchyma cells.**

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