Association of Zoochlorella and Hydra is the example of

Options

A. parasitism
B. mutualism
C. cohabitation
D. commensalism

Answer

**Step-by-Step Solution:**

1. **Identify the Organisms Involved**: The question refers to the association between Zoochlorella, a type of algae, and Hydra, a freshwater organism belonging to the phylum Cnidaria.

2. **Understand the Nature of Their Relationship**: To determine the type of association, we need to analyze how both organisms interact and what benefits they derive from each other.

3. **Define Mutualism**: Mutualism is a symbiotic relationship where both organisms benefit from the association.

4. **Examine the Benefits to Zoochlorella**:
- Zoochlorella lives inside the nutritive cells of Hydra.
- It benefits by obtaining carbon dioxide, phosphorus, and nitrogenous waste from Hydra, which are essential for its growth and photosynthesis.

5. **Examine the Benefits to Hydra**:
- Hydra benefits from Zoochlorella by receiving oxygen and essential nutrients produced by the algae through photosynthesis.
- Additionally, the presence of Zoochlorella gives Hydra its green color.

6. **Conclusion**: Since both organisms benefit from the relationship, it is classified as mutualism. Therefore, the correct answer to the question is option 2: mutualism.