Zoospores are absent in

Options

A. Vaucheria
B. Spirogyra
C. Cladophora
D. Chlamydomonas.

Answer

To solve the question "Zoospores are absent in," we need to analyze the given options: Vicaria, Spirogyra, Cladophora, and Chlamydomonas.

### Step-by-Step Solution:

1. **Understand Zoospores**:
- Zoospores are motile spores that are capable of swimming due to the presence of flagella. They are typically found in certain algae and fungi.

2. **Examine Each Option**:
- **Vicaria**: This is a genus of green algae that produces zoospores.
- **Spirogyra**: This is a filamentous green alga that reproduces sexually through the formation of zygospores. It does not produce zoospores.
- **Cladophora**: This is another type of green algae that can produce zoospores.
- **Chlamydomonas**: This is a unicellular green alga known for its motile zoospores.

3. **Identify the Correct Answer**:
- Among the options, Spirogyra is the only one that does not produce zoospores. Instead, it reproduces through zygospores, which are the only diploid stage in its life cycle.

4. **Conclusion**:
- Therefore, the correct answer to the question "Zoospores are absent in" is **Spirogyra**.

### Final Answer:
**Spirogyra**