Living mechanical tissue is

Options

A. collenchyma
B. parenchyma
C. sclerenchyma
D. complex tissue

Answer

To solve the question "Living mechanical tissue is," we need to analyze the options provided: collenchyma, parenchyma, sclerenchyma, and complex tissue.

### Step-by-Step Solution:

1. **Understanding Mechanical Tissues**:
- Mechanical tissues provide structural support to plants. They can be living or dead.

2. **Identifying Living Mechanical Tissues**:
- **Collenchyma**: This is a living mechanical tissue. It consists of elongated cells with irregularly thickened cell walls, primarily composed of pectin and cellulose. It provides support, especially in growing shoots and leaves.
- **Parenchyma**: While it is a living tissue, it primarily serves functions like photosynthesis, storage, and secretion, rather than mechanical support.
- **Sclerenchyma**: This tissue is primarily dead at maturity and is responsible for providing support. It has thick lignified walls and does not have living protoplasts.
- **Complex Tissue**: This includes xylem and phloem, which are involved in the transport of water and nutrients, not specifically mechanical support.

3. **Conclusion**:
- Among the options, **collenchyma** is the only living mechanical tissue that provides structural support to growing parts of the plant.

### Final Answer:
**Living mechanical tissue is collenchyma.**