Plant movement in response to diffuse stimulus of light is

Options

A. Phototropism
B. Photolysis
C. Phototaxis
D. Photonasty.

Answer

To answer the question "Plant movement in response to diffuse stimulus of light is," we will analyze the options provided: phototropism, photolysis, phototaxis, and photonasty.

### Step-by-Step Solution:

1. **Understanding Phototropism**:
- Phototropism refers to the growth of a plant in response to light.
- This is a directional growth movement where the plant bends towards the light source.
- **Conclusion**: This option is not correct because the question specifically asks for movement, not growth.

2. **Understanding Photolysis**:
- Photolysis is the process of breaking down water molecules in the presence of sunlight, which is a part of photosynthesis.
- This term does not relate to plant movement.
- **Conclusion**: This option is also not correct as it does not pertain to plant movement in response to light.

3. **Understanding Phototaxis**:
- Phototaxis refers to the movement of an organism (including plants) in response to light, specifically diffuse sunlight.
- This is the correct term for the movement of plants towards or away from light.
- **Conclusion**: This option is correct as it directly addresses the question about plant movement in response to diffuse light.

4. **Understanding Photonasty**:
- Photonasty refers to non-directional movements of plants in response to light.
- These movements do not involve growth towards or away from the light source but rather a response that is not directional.
- **Conclusion**: This option is incorrect as it does not describe directional movement in response to light.

### Final Answer:
The correct answer is **phototaxis** (option number 3).