_________ heterotrophic in nature and do not possess chlorophyll or a cell wall.

Options

A. Protozoans
B. Parasites
C. Fungi
D. Virus

Answer

To answer the question: "_________ heterotrophic in nature and do not possess chlorophyll or a cell wall," we need to identify the correct organism from the options provided: protozoans, parasites, fungi, or virus.

### Step-by-Step Solution:

1. **Understanding Heterotrophic Nature**:
- Heterotrophic organisms cannot produce their own food and must obtain nutrition from other sources. This means they rely on organic compounds from their environment.

2. **Identifying the Characteristics**:
- The question specifies that the organism does not possess chlorophyll, which means it cannot perform photosynthesis.
- It also states that the organism does not have a cell wall, which is a key feature to consider.

3. **Analyzing the Options**:
- **Protozoans**: These are unicellular eukaryotic organisms. They are heterotrophic and do not have a cell wall. They obtain their nutrition from their environment.
- **Parasites**: While many parasites are heterotrophic, they can belong to different groups and may have different structures.
- **Fungi**: Fungi are also heterotrophic, but they have a cell wall made of chitin.
- **Virus**: Viruses are not classified as living organisms in the traditional sense and do not have a cellular structure, but they do not fit the criteria of being heterotrophic like the others.

4. **Conclusion**:
- Based on the characteristics outlined, the correct answer is **protozoans**, as they are heterotrophic, lack chlorophyll, and do not possess a cell wall.

### Final Answer:
**Protozoans**