The colour of red snow is due to

Options

A. Chlamydomonas snowiae
B. Chlamydomonas nivalis
C. Both A and B
D. None of the above.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the cause of the red color in snow, specifically what organism is responsible for this phenomenon.

2. **Identifying Possible Answers**: The options provided are:
- A. Chlamydomonas noviae
- B. Chlamydomonas nivalis
- C. Both A and B
- D. None of the above

3. **Researching the Organisms**:
- Chlamydomonas is a genus of green algae.
- Chlamydomonas nivalis is known to thrive in cold environments, particularly in snow and ice.

4. **Analyzing the Characteristics of Chlamydomonas nivalis**:
- This specific species of algae contains red pigments (carotenoids) that give the snow its reddish color.
- It is commonly found in snowfields and is adapted to cold temperatures.

5. **Considering the Other Options**:
- Chlamydomonas noviae is not typically associated with red snow, and thus does not contribute to the phenomenon.
- Option C (both A and B) is incorrect since only one organism is responsible.
- Option D (none of the above) is also incorrect as Chlamydomonas nivalis is indeed responsible.

6. **Conclusion**: Based on the information gathered, the correct answer to the question is B. Chlamydomonas nivalis.

**Final Answer**: B. Chlamydomonas nivalis

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