Mutualism is found in

Options

A. hermit crab and sea-anemone
B. butterfly and flower
C. zoochlorellac and Hydra
D. E.coli and man.

Explanation

To determine which of the given options represents mutualism, we need to analyze each option based on the definition of mutualism. Mutualism is a type of symbiotic relationship where both species involved benefit from the interaction.

### Step-by-Step Solution:

1. **Understand Mutualism**:
- Mutualism is a positive interaction between two different species where both benefit from the relationship.

2. **Analyze Each Option**:
- **Option 1: Hermit Crab and Sea Anemone**:
- The hermit crab carries the sea anemone on its shell, and in return, the anemone provides protection to the crab. This is a mutualistic relationship.
- **Option 2: Butterfly and Flower**:
- Butterflies feed on nectar from flowers while helping in pollination. Both the butterfly and the flower benefit, making this a mutualistic relationship.
- **Option 3: Zoochlorella and Hydra**:
- Zoochlorella (a type of algae) lives within Hydra and provides it with nutrients through photosynthesis, while Hydra provides carbon dioxide and nitrogenous waste to the algae. This is also a mutualistic relationship.
- **Option 4: E. coli and Man**:
- E. coli in the human gut helps in digestion and synthesizes certain vitamins, while the bacteria benefit from the nutrients in the human gut. This is another example of mutualism.

3. **Conclusion**:
- All four options represent mutualistic relationships, but if we are to select one based on the context provided, **Option 3: Zoochlorella and Hydra** is highlighted as a clear example of mutualism in the explanation.

### Final Answer:
Mutualism is found in **Zoochlorella and Hydra**.