Which one of the following are intracellular obligate parasites

Options

A. Bacteria
B. Viruses
C. Slime moulds
D. Blue-green algae

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Intracellular Obligate Parasites":**
- Intracellular obligate parasites are organisms that can only reproduce and live inside the cells of a host organism. They cannot survive outside of a host.

2. **Analyzing the Options:**
- **Bacteria:** These are generally not obligate intracellular parasites. Many bacteria can live independently outside of host cells.
- **Viruses:** Viruses are unique in that they cannot reproduce or carry out metabolic processes outside of a host cell. They are considered obligate intracellular parasites because they require a host cell to replicate.
- **Slime Molds:** These are protists that can live independently in the environment and do not require a host to survive.
- **Blue-Green Algae:** Also known as cyanobacteria, these organisms can photosynthesize and live independently in aquatic environments.

3. **Identifying the Correct Answer:**
- Among the given options, only **viruses** are classified as intracellular obligate parasites since they can only exist and reproduce within a host cell.

4. **Conclusion:**
- The correct answer is **viruses**.

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