What is common about Trypanosoma, Noctiluca Monocystis and Giardia

Options

A. These are all unicellular protists
B. They have flagella
C. They produce spores
D. These are all parasites

Answer

### Step-by-Step Solution:

1. **Identify the Organisms**: The question asks about Trypanosoma, Noctiluca, Monocystis, and Giardia. These are all specific types of organisms that belong to the category of protists.

2. **Classify the Organisms**:
- **Trypanosoma**: This is a unicellular organism known for causing diseases such as sleeping sickness. It is classified as a zooflagellate.
- **Noctiluca**: This is a marine dinoflagellate that is also unicellular and colorless.
- **Monocystis**: This organism is an endoparasitic protozoan that lives within the coelom of earthworms.
- **Giardia**: Known as the "grand old man of the intestine," Giardia is a flagellated protozoan that causes diarrhea.

3. **Determine Common Characteristics**:
- All four organisms are unicellular, meaning they consist of a single cell.
- They are classified under the kingdom Protista, which includes various unicellular organisms.
- While some of them have flagella (like Trypanosoma and Giardia), not all do (Monocystis does not require locomotion as it is an endoparasite).
- They are not all parasites; for instance, Noctiluca is not a parasite but a free-living dinoflagellate.

4. **Conclusion**: The main commonality among Trypanosoma, Noctiluca, Monocystis, and Giardia is that they are all unicellular protists.

### Final Answer:
The common characteristic of Trypanosoma, Noctiluca, Monocystis, and Giardia is that they are all unicellular protists.

---