Evolution does not occur in case of

Options

A. Parasitism
B. Mutualism
C. Both (1) and (2)
D. Commensalism

Answer

### Step-by-Step Solution:

1. **Understanding Co-evolution**: Co-evolution refers to the process where two or more species influence each other's evolutionary trajectory. This typically occurs in interactions where species have a close ecological relationship.

2. **Identifying Types of Interactions**: There are several types of ecological interactions, including:
- **Parasitism**: One organism (the parasite) benefits at the expense of another (the host).
- **Mutualism**: Both organisms benefit from the interaction.
- **Commensalism**: One organism benefits while the other is neither helped nor harmed.

3. **Analyzing Parasitism**: In parasitism, the parasite derives benefits (food, habitat) from the host, while the host suffers. Despite the negative impact on the host, both organisms can still evolve in response to each other, indicating that co-evolution occurs in this relationship.

4. **Analyzing Mutualism**: In mutualism, both species benefit from the relationship, and they often evolve together to enhance their mutual benefits. For example, lichens consist of fungi and algae that co-evolve to thrive together.

5. **Analyzing Commensalism**: In commensalism, one organism benefits while the other is unaffected. Since there is no reciprocal influence on the evolution of the other species, co-evolution does not occur in this type of interaction.

6. **Conclusion**: Given the definitions and analysis of the three types of interactions, the correct answer to the question "Evolution does not occur in case of" is **commensalism**.

### Final Answer:
Co-evolution does not occur in the case of **commensalism**.

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