An underground stem without adventitious roots is

Options

A. Potato
B. Onion
C. Colocacia
D. All correct.

Answer

To solve the question "An underground stem without adventitious roots is," we need to analyze the options provided and determine which one fits the criteria of being an underground stem and lacking adventitious roots.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for an underground stem that does not have adventitious roots. Adventitious roots are those that arise from parts of the plant other than the root system, typically from the stem or leaves.

2. **Identify the Options**: The options given are:
- A) Potato
- B) Onion
- C) Colocasia

3. **Evaluate Each Option**:
- **Option A: Potato**
- The potato is a modified stem known as a tuber.
- It grows underground and does not produce adventitious roots.
- Therefore, this option fits the criteria.

- **Option B: Onion**
- The onion is a bulb, which is also a modified stem.
- However, it has adventitious roots that grow from the base of the bulb.
- Thus, this option does not fit the criteria.

- **Option C: Colocasia**
- Colocasia, like the potato, is also an underground stem.
- However, it too has adventitious roots.
- Therefore, this option does not fit the criteria either.

4. **Conclusion**: After evaluating all options, the only underground stem that does not have adventitious roots is the potato.

### Final Answer:
**The correct answer is A) Potato.**

---