Phytochrome is

Options

A. Light receptor
B. Dark receptor
C. Photosynthetic pigment
D. A light sensitive hormone

Answer

### Step-by-Step Solution:

1. **Definition of Phytochrome**: Phytochrome is a photoreceptor protein found in plants that is sensitive to light. It plays a crucial role in detecting light and regulating various plant growth and developmental processes.

2. **Function of Phytochrome**: The primary function of phytochrome is to absorb light and help the plant determine the direction of light. This allows the plant to grow towards the light source, optimizing its exposure to sunlight for photosynthesis.

3. **Role in Photosynthesis**: While phytochrome itself is not a photosynthetic pigment, it facilitates the process of photosynthesis by ensuring that the plant grows towards areas with more light. This enhances the plant's ability to produce food through photosynthesis.

4. **Classification of Phytochrome**: Phytochrome is classified as a light receptor. It is not a dark receptor, nor is it a photosynthetic pigment or a hormone. Its primary role is to respond to light conditions, thus guiding plant growth.

5. **Conclusion**: Therefore, phytochrome can be defined as a light receptor that helps plants sense light direction and optimize their growth accordingly.