Heterothallism is found in

Options

A. Mucor
B. Cycas
C. Selaginella
D. Volvox.

Answer

**Step-by-Step Solution:**

1. **Understanding Heterothallism**: Heterothallism refers to a condition in fungi where there are two different types of mycelia involved in sexual reproduction. This means that the fungi have two distinct mating types, often referred to as "A" and "B".

2. **Characteristics of Heterothallic Fungi**: In heterothallic fungi, the two types of mycelia (A and B) are necessary for sexual reproduction. Mycelium A may represent the male type, while mycelium B represents the female type. Both types must come together for reproduction to occur.

3. **Identifying Examples**: To answer the question, we need to identify which of the given options is a fungus that exhibits heterothallism. The options provided are:
- A) Mucor
- B) Cycas
- C) Selaginella
- D) Walwaxi

4. **Analyzing the Options**:
- **Mucor**: This is a genus of fungi that exhibits heterothallism.
- **Cycas**: This is a type of gymnosperm, not a fungus.
- **Selaginella**: This belongs to the pteridophyta group and is also not a fungus.
- **Walwaxi**: This is a green algae, not related to fungi.

5. **Conclusion**: Based on the analysis, the correct answer is **A) Mucor**, as it is the only option that represents a fungus exhibiting heterothallism.