Photosynthetic pigments common to all algae :-

Options

A. Chlorophyll 'b' and carotene
B. Chlorophyll 'a' and 'b'
C. Chlorophyll 'a' and carotene
D. Chlorophyll and xanthophyll

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the photosynthetic pigments that are common to all algae. Algae are a diverse group of photosynthetic organisms, and understanding which pigments are universally present is key.

2. **Identifying Photosynthetic Pigments**: The main photosynthetic pigments include chlorophyll (specifically chlorophyll A), carotenes, and xanthophylls. We need to determine which of these are found in all types of algae.

3. **Role of Chlorophyll**: Chlorophyll A is the primary pigment involved in photosynthesis across all algae. It acts as a reaction center, absorbing light energy and converting it into chemical energy.

4. **Role of Carotenes**: Carotenes are another group of pigments that assist in light absorption. They absorb light in different ranges compared to chlorophyll and help transfer energy to chlorophyll A.

5. **Examining Xanthophylls**: Xanthophylls are pigments that are primarily found in specific groups of algae, such as brown algae (Phaeophyceae) and some green algae (Chlorophyceae). However, they are not universally present in all algae, particularly absent in red algae and blue-green algae.

6. **Conclusion**: Based on the analysis, the pigments that are common to all algae are chlorophyll A and carotenes. Chlorophyll B and xanthophylls are not found in all algae.

7. **Final Answer**: The photosynthetic pigments common to all algae are **Chlorophyll A and Carotenes**.