On the basis of host attacked viruses are classified into

Options

A. two
B. three
C. four
D. five

Explanation

**Step-by-Step Solution:**

1. **Understanding Viruses**: Begin by recognizing that viruses are unique entities that exist in a non-living state outside of a host organism. They require a host to replicate and exhibit living characteristics.

2. **Classification Based on Host**: Viruses can be classified based on the type of host they infect. The primary categories include:
- **Plant Viruses**: These viruses specifically infect plant cells and can cause various diseases in plants.
- **Animal Viruses**: These viruses infect animal cells, including humans, and can lead to a range of illnesses.
- **Bacterial Viruses (Bacteriophages)**: These are viruses that specifically target and infect bacteria.

3. **Additional Classifications**: While the main classifications are plant, animal, and bacterial viruses, there are also other types of viruses that can infect different organisms, such as:
- **Phycophages**: Viruses that infect algae.
- **Mycophages**: Viruses that infect fungi.
However, these are less commonly referenced in basic classifications.

4. **Conclusion**: Based on the primary classifications of viruses according to the host they attack, the answer to the question is that viruses are classified into three main categories: plant viruses, animal viruses, and bacterial viruses.

5. **Final Answer**: Therefore, the correct option is three.

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