Which of the following is true ?

Options

A. Vessels are unicellular and with narrow lumen
B. Vessels are multicellular and with wide lumen
C. Tracheids are unicellular and with wide lumen
D. Tracheids are multicellular and with narrow lumen

Answer

To determine which statement is true regarding vessels and tracheids in the xylem, we can analyze the characteristics of these structures step by step.

### Step-by-Step Solution:

1. **Understanding Vessels and Tracheids**:
- Vessels and tracheids are both components of xylem tissue in plants, responsible for the conduction of water and minerals.
- Vessels are typically wider and more efficient in conducting water compared to tracheids.

2. **Characteristics of Vessels**:
- Vessels are **multicellular** structures, meaning they are made up of multiple cells.
- They have **wide lumens** (the hollow part through which water flows), which allows for more efficient water transport.
- Vessels are **lignified**, meaning they have lignin deposited in their cell walls, making them strong and providing structural support.

3. **Characteristics of Tracheids**:
- Tracheids are also **multicellular** but are generally narrower than vessels.
- They have **narrow lumens**, which makes them less efficient than vessels in conducting water.

4. **Evaluating the Options**:
- Option 1: "Vessels are unicellular with narrow lumens." - This is false.
- Option 2: "Vessels are multicellular with wide lumens." - This is true.
- Option 3: "Tracheids are unicellular with wide lumens." - This is false.
- Option 4: "Tracheids are multicellular with narrow lumens." - This is true, but it does not answer the question about vessels.

5. **Conclusion**:
- The correct statement from the options given is: **"Vessels are multicellular with wide lumens."**

### Final Answer:
**Option 2: Vessels are multicellular with wide lumens.**

---