Which of these algae would you be able to see even without a microscope?

Options

A. Spirogyra
B. Chlorella
C. Volvox
D. Fucus

Answer

To determine which of the given algae can be seen without a microscope, we will analyze each option based on their size and visibility to the naked eye.

### Step-by-Step Solution:

1. **Understanding the Visibility of Algae**:
- The human eye can typically see objects that are larger than 0.1 mm. Any object smaller than this requires a microscope to be observed.

2. **Analyzing Each Option**:
- **A. Spirogyra**:
- Spirogyra is a green filamentous algae. It consists of long, thin filaments that are made of single cells. These filaments are generally too small to be seen without a microscope.
- **B. Chlorella**:
- Chlorella is a unicellular green algae. Being unicellular, it is microscopic and cannot be seen without the aid of a microscope.
- **C. Volvox**:
- Volvox is a colonial green algae. While it forms colonies, these colonies are often still too small to be seen without a microscope, depending on the specific species.
- **D. Fucus**:
- Fucus is a brown algae that can grow quite large, up to 50 cm in size. This size is well above the threshold of visibility for the naked eye.

3. **Conclusion**:
- Among the options provided, **D. Fucus** is the only algae that can be seen without a microscope due to its larger size.

### Final Answer:
**D. Fucus**