Which of these algae is multicellular?

Options

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

Answer

To determine which of the listed algae is multicellular, we can follow these steps:

### Step 1: Understand the Definitions
- **Unicellular organisms** are made up of a single cell.
- **Multicellular organisms** are composed of multiple cells.

### Step 2: Identify the Algae Types
The algae mentioned in the question are:
1. Chlamydomonas
2. Spirogyra
3. Chlorella
4. Volvox

### Step 3: Classify Each Alga
- **Chlamydomonas**: This is a unicellular green alga.
- **Spirogyra**: This is also a unicellular green alga.
- **Chlorella**: This is another example of unicellular algae.
- **Volvox**: This is a multicellular alga that forms colonies.

### Step 4: Conclusion
From the classification, we can conclude that **Volvox** is the only multicellular alga among the options provided.

### Final Answer
The multicellular alga is **Volvox**.

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