Secondary was is not formed in

Options

A. Companion cells
B. Collenchyma
C. Parenchyma
D. All the above

Answer

To solve the question "Secondary wall is not formed in," we need to analyze the options provided and understand the characteristics of the cell types mentioned.

### Step-by-Step Solution:

1. **Understanding Secondary Walls**:
- Secondary walls are additional layers of cell wall material that are deposited inside the primary cell wall after the cell has stopped growing. They provide additional strength and support to the plant.

2. **Analyzing the Options**:
- **Option 1: Companion Cell**:
- Companion cells are found in the phloem and do have secondary walls. Therefore, they do not fit the criteria of the question.

- **Option 2: Collenchyma**:
- Collenchyma cells have unevenly thickened primary walls that provide support to young plant tissues. They do not typically have secondary walls, but they are often considered to have some characteristics similar to secondary walls. However, they are primarily known for their primary walls.

- **Option 3: Parenchyma**:
- Parenchyma cells are the most common type of plant cells and have thin primary walls. They do not form secondary walls. This makes parenchyma a strong candidate for the answer.

- **Option 4: All of the above**:
- Since both companion cells and collenchyma do have secondary walls, this option cannot be correct.

3. **Conclusion**:
- The only cell type from the options that does not form secondary walls is **Parenchyma**. Thus, the correct answer is **Option 3: Parenchyma**.

### Final Answer:
**Parenchyma** is the correct answer as it does not form secondary walls.

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