Ulothrix and Spirogyra are :

Options

A. Colonial and branched
B. Solitary and branched
C. Filamentous and unbranched
D. Filamentous and branched

Answer

To solve the question "Ulothrix and Spirogyra are:", we need to analyze the characteristics of both Ulothrix and Spirogyra.

### Step-by-Step Solution:

1. **Identify the Type of Algae**:
- Both Ulothrix and Spirogyra are types of green algae. They belong to the class of algae known as Chlorophyceae.

2. **Examine the Structure**:
- Ulothrix is a filamentous green alga. It consists of unbranched filaments, which means that the cells are arranged in long chains without any branching.
- Spirogyra is also filamentous and is characterized by its spiral-shaped chloroplasts. Like Ulothrix, Spirogyra is also unbranched.

3. **Evaluate the Options**:
- The options provided include:
- Colonial and Branched
- Solitary and Branched
- Filamentous and Unbranched
- Filamentous and Branched
- Based on our analysis, both Ulothrix and Spirogyra are filamentous and unbranched.

4. **Select the Correct Option**:
- The correct answer is **"Filamentous and Unbranched"**. This aligns with the characteristics of both Ulothrix and Spirogyra.

### Final Answer:
Ulothrix and Spirogyra are **Filamentous and Unbranched**.

---