Which one is true ?

Options

A. vessels are multicellular with dide lumen
B. Vessels are unicelluar with narrow lumen.
C. Tracheids are mutlicullar with narrow lumen.
D. Tracheids are unicellular with wide lumen.

Answer

To determine which statement is true regarding vessels and tracheids, we can analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Vessels:**
- Vessels are a type of water-conducting tissue in plants.
- They are composed of vessel elements that are arranged end to end.
- Each vessel element is a part of a multicellular structure.

2. **Analyzing Option A:**
- Option A states: "Vessels are multicellular with wide lumen."
- This statement is correct because vessels are indeed multicellular and have a wide lumen (the internal space).

3. **Analyzing Option B:**
- Option B states: "Vessels are unicellular with narrow lumen."
- This statement is incorrect because vessels are multicellular, not unicellular, and they have a wide lumen.

4. **Analyzing Option C:**
- Option C states: "Tracheids are multicellular with narrow lumen."
- This statement is incorrect because tracheids are unicellular and have a narrow lumen.

5. **Analyzing Option D:**
- Option D states: "Tracheids are unicellular with wide lumen."
- This statement is also incorrect because tracheids are unicellular but have a narrow lumen.

6. **Conclusion:**
- After analyzing all options, the only true statement is Option A: "Vessels are multicellular with wide lumen."

### Final Answer:
The correct answer is **Option A: Vessels are multicellular with wide lumen.**

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