In xylem, strength is provided by

Options

A. vessels
B. fibres
C. parenchyma
D. 1 and 2

Answer

### Step-by-Step Solution:

1. **Understanding Xylem Composition**:
- Xylem consists of four main components: tracheids, vessels, fibers, and parenchyma.
- Each of these components has a specific role in the functioning of xylem.

2. **Role of Tracheids**:
- Tracheids are elongated, dead cells that have thickened cell walls, which provide some mechanical strength to the plant.
- They have an unequal thickness in their cell walls, which contributes to their structural integrity.

3. **Role of Vessels**:
- Vessels are also part of xylem and are arranged end to end, allowing for efficient water conduction.
- However, vessels have thinner cell walls compared to tracheids, making them less rigid and in need of additional support.

4. **Role of Fibers**:
- Fibers are specialized cells that provide mechanical support to the xylem.
- Since vessels have thinner walls and require support to withstand the pressure of sap, fibers fulfill this role.

5. **Role of Parenchyma**:
- Parenchyma cells serve primarily as storage tissue and do not contribute to the mechanical strength of xylem.

6. **Conclusion**:
- In summary, while tracheids contribute to strength, they do not require mechanical support. Vessels need support due to their thin walls, and this support is provided by fibers.
- Therefore, the component that provides strength in xylem is **fibers**.

### Final Answer:
**Fibers provide strength in xylem.**

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