Cyanobacteria are

Options

A. heterotrophs
B. chemotrophs
C. autotrophs
D. organotrophs

Explanation

**Step-by-Step Solution:**

1. **Understanding Cyanobacteria**: Begin by recognizing that cyanobacteria are a type of bacteria that are known for their ability to perform photosynthesis. They are often referred to as blue-green algae, although they are not true algae.

2. **Identifying Characteristics**: Cyanobacteria have several key characteristics:
- They are photosynthetic organisms, meaning they can produce their own food using sunlight.
- They contain chlorophyll a, which is essential for photosynthesis.
- They are prokaryotic, meaning they lack a nucleus and other membrane-bound organelles.
- They are gram-negative bacteria.

3. **Analyzing the Options**: The question provides four options regarding the nutritional classification of cyanobacteria:
- A. Heterotrophs: Organisms that cannot produce their own food and must consume organic matter.
- B. Haemotrophs: This term is not commonly used in biological classification.
- C. Autotrophs: Organisms that can produce their own food. This includes photoautotrophs, which use light energy.
- D. Organotrophs: Organisms that obtain electrons or hydrogen from organic substances.

4. **Determining the Correct Classification**: Since cyanobacteria can produce their own food through photosynthesis, they fall under the category of autotrophs. More specifically, they are classified as photoautotrophs because they utilize light energy for this process.

5. **Conclusion**: Based on the characteristics and definitions discussed, the correct answer to the question "Cyanobacteria are" is option C: Autotrophs.

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