The dead, elongated cells having lignified thick cell wall occurring in groups, with tapering ends and serving a me chanical function are called -

Options

A. Fibres
B. Vessels
C. Tracheids
D. Collenchyma

Answer

To solve the question regarding the type of cells described, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Characteristics**: The question describes dead, elongated cells with a lignified (woody) thick cell wall, occurring in groups, having tapering ends, and serving a mechanical function.

2. **Understand the Options**: The options given are fibres, vessels, tracheids, and collenchyma. We need to analyze each option based on the characteristics provided.

3. **Analyze Each Option**:
- **Fibres**: These are indeed dead, elongated cells with thick lignified walls. They are grouped together and provide mechanical support to the plant.
- **Vessels**: These are also conducting elements but are not primarily for mechanical support. They are typically wider and more specialized for water transport.
- **Tracheids**: Similar to vessels, tracheids are involved in water conduction but are also not primarily mechanical support cells.
- **Collenchyma**: These cells are living, have unevenly thickened walls, and provide flexible support, but they do not have lignified walls.

4. **Conclusion**: Based on the analysis, the cells that fit all the criteria (dead, elongated, lignified, grouped, tapering ends, and mechanical function) are **fibres**.

5. **Final Answer**: The correct answer is **fibres**.