The closing and opening of the leaves of Mimosa pudica is due to

Options

A. thigmonastic movement
B. hydrotropic movement
C. seismonastic movement
D. chemonastic movement

Explanation

### Step-by-Step Solution:

1. **Identify the Plant**: The plant in question is Mimosa pudica, commonly known as the touch-me-not plant.

2. **Understand the Movement**: The leaves of Mimosa pudica exhibit a unique behavior where they close or droop when touched. This response is a defense mechanism to deter herbivores or respond to environmental stimuli.

3. **Type of Movement**: The movement of the leaves in response to touch is classified as a type of nastic movement. Specifically, it is known as **thigmonastic movement**. This term comes from "thigmo," which refers to touch.

4. **Mechanism of Movement**: When the leaves are touched, there is a change in turgor pressure within the cells of the leaf. Turgor pressure is the pressure of the cell contents against the cell wall, which helps maintain the plant's structure.

5. **Propagation of Response**: The change in turgor pressure spreads from cell to cell, leading to the rapid closing of the leaves. The speed of this response can vary depending on the intensity of the touch.

6. **Duration of Response**: After the initial closing, it takes about 10 to 15 minutes for the leaves to return to their original position.

7. **Conclusion**: The correct answer to the question is that the closing and opening of the leaves of Mimosa pudica is due to **thigmonastic movement**.