Chlamydomonas nivalis colours the snow

Options

A. Red
B. Yellow
C. Green
D. Purple brown.

Answer

### Step-by-Step Solution:

1. **Identify the Organism**: The question refers to *Chlamydomonas nivalis*, which is a type of algae.

2. **Classify the Algae**: *Chlamydomonas nivalis* belongs to the green algae group, specifically within the genus *Chlamydomonas*.

3. **Color of the Algae**: This species is known for its red pigmentation, which is due to the presence of carotenoids.

4. **Habitat**: *Chlamydomonas nivalis* is typically found in snowy environments, such as polar regions and mountainous areas.

5. **Phenomenon of Watermelon Snow**: The presence of *Chlamydomonas nivalis* in snow leads to a phenomenon known as "watermelon snow," where the snow appears red or pink due to the algae's pigmentation.

6. **Determine the Correct Color**: Among the options provided (red, yellow, green, purple-brown), the red color is the correct answer since *Chlamydomonas nivalis* causes the snow to appear red.

7. **Conclusion**: Therefore, the correct answer to the question is that *Chlamydomonas nivalis* colors the snow red.