Thigmotropism is best seen in

Options

A. Root apex
B. Stem apex
C. Leaf apex
D. Tendrils

Answer

### Step-by-Step Solution:

1. **Understanding Thigmotropism**:
- Thigmotropism is a growth response of plants to touch or physical contact with solid objects. It is a type of tropism where the direction of growth is influenced by touch.

2. **Identifying the Plant Parts**:
- In the options provided, we have:
- A) Root of X
- B) Stem of X
- C) Leaf of X
- D) Tendril of X

3. **Analyzing Each Option**:
- **Roots**: Generally, roots exhibit gravitropism (response to gravity) rather than thigmotropism.
- **Stems**: While stems can respond to touch, they do not exhibit thigmotropic behavior as distinctly as tendrils.
- **Leaves**: Leaves do not typically show thigmotropism; they are not designed to coil around objects.
- **Tendrils**: Tendrils are specialized structures that are highly responsive to touch. When they come in contact with a solid object, they coil around it, which is a clear example of thigmotropism.

4. **Conclusion**:
- Based on the analysis, thigmotropism is best seen in tendrils, which are adapted for climbing and support. Therefore, the correct answer is **Option D: Tendril of X**.