A parasitic green alga is

Options

A. Chlorella
B. Ulva
C. Cladophora
D. Cephaleuros.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a specific type of green alga that is parasitic. We need to identify which of the given options is a parasitic green alga.

2. **Analyzing the Options**:
- **Option 1: Chlorella**: This is a genus of single-celled green algae that is not known to be parasitic. It is primarily used in nutrition and does not depend on other plants for survival.
- **Option 2: Alba**: This refers to a group of edible green algae, which are also not parasitic. They are typically consumed as food and do not harm other plants.
- **Option 3: Cladophora**: This is another genus of green algae that grows attached to rocks or submerged timber in freshwater environments. It is not a parasite.
- **Option 4: Cephalurus**: This is identified as a parasitic green alga. Specifically, Cephalurus viridis is known to infect various higher plants, including tea, coffee, coconut, and guava.

3. **Conclusion**: After analyzing each option, it is clear that the only parasitic green alga among the choices is **Cephalurus**. Therefore, the correct answer is **Option 4: Cephalurus**.

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