The pigment which mainly absorbs red and far-red radiation in plants, is known as

Options

A. xanthophyll
B. cytochrome
C. phytochrome
D. carotene

Explanation

**Step-by-Step Solution:**

1. **Identify the Question:** The question asks for the pigment in plants that primarily absorbs red and far-red radiation.

2. **Understand the Options:** The options provided include various pigments. It is essential to differentiate between them based on their functions:
- **Xanthophylls and Carotenes:** These are photosynthetic pigments involved in the process of photosynthesis, primarily absorbing light in the blue and green wavelengths.
- **Cytochromes:** These pigments are involved in the electron transport chain and contain iron or copper. They are not primarily involved in light absorption for photosynthesis.
- **Phytochrome:** This is a photoreceptor pigment that specifically absorbs red (around 660 nm) and far-red light (around 730 nm).

3. **Determine the Correct Pigment:** Since the question specifically asks about the pigment that absorbs red and far-red light, we focus on phytochrome. It is known for its role in regulating various plant processes, including flowering, based on light exposure.

4. **Explain the Function of Phytochrome:** Phytochrome exists in two forms: Pr (absorbs red light) and Pfr (absorbs far-red light). The conversion between these two forms is crucial for photoperiodic responses in plants, such as flowering.

5. **Conclude the Answer:** Based on the understanding of the pigments and their functions, the correct answer to the question is **phytochrome**.

**Final Answer:** The pigment which mainly absorbs red and far-red radiation in plants is known as **phytochrome**.

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