Chlamydomonas is an unicellular green ........

Explanation

**Step-by-Step Solution:**

1. **Identify the Organism**: Chlamydomonas is the organism we are discussing. It is important to recognize that it belongs to the group of organisms known as algae.

2. **Determine the Type of Algae**: Chlamydomonas is classified specifically as a green alga. This classification is based on its pigmentation and the type of chlorophyll it contains.

3. **Understand the Cellular Structure**: Chlamydomonas is unicellular, meaning it consists of a single cell. This distinguishes it from multicellular algae.

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