Name the unicellular or multicellular autotrophic microorganism.

Options

A. Algae
B. Protozoa
C. Bacteria
D. Fungi

Explanation

**Step-by-Step Solution:**

1. **Understanding the Types of Microorganisms**: Microorganisms can be classified into different categories based on their nutritional modes. The main types include autotrophic and heterotrophic microorganisms. Autotrophic microorganisms can produce their own food, while heterotrophic microorganisms cannot.

2. **Identifying Autotrophic Microorganisms**: Among the options provided (algae, protozoa, bacteria, fungi), we need to identify which ones are autotrophic. Autotrophic microorganisms are capable of photosynthesis or chemosynthesis to create their own food.

3. **Analyzing the Options**:
- **Algae**: Algae are primarily autotrophic and can be unicellular (like Chlorella) or multicellular (like giant kelp). They contain chlorophyll, which allows them to perform photosynthesis.
- **Protozoa**: Protozoa are generally heterotrophic and do not produce their own food.
- **Bacteria**: While some bacteria are autotrophic (like cyanobacteria), many are heterotrophic. However, they are not typically classified as a primary example of autotrophic microorganisms in this context.
- **Fungi**: Fungi are heterotrophic and cannot produce their own food.

4. **Conclusion**: Based on the analysis, the correct answer is **algae**, as they are the only option that can be either unicellular or multicellular and are autotrophic.

5. **Final Answer**: The unicellular or multicellular autotrophic microorganism is **algae**.

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