Polio' is caused by

Options

A. Bacteriophage
B. Virus with a single strand RNA
C. Virus with a single strand DNA
D. Virus with double strand DNA

Answer

### Step-by-Step Solution:

1. **Identify the Causative Agent**: The first step is to determine what causes polio. Polio is caused by a specific virus known as the poliovirus.

2. **Understand the Nature of the Virus**: The poliovirus is classified as an RNA virus. It contains RNA as its genetic material, which is crucial for its replication and infection process.

3. **Differentiate Between Types of Viruses**: Viruses can be categorized based on their genetic material. They can be single-stranded RNA, double-stranded RNA, single-stranded DNA, or double-stranded DNA. Since polio is caused by the poliovirus, it is important to note that it is not a bacteriophage or a virus with DNA.

4. **Mechanism of Infection**: When the poliovirus enters the host body, it utilizes the host's cellular machinery to replicate. The RNA of the virus is crucial for this process, and it can be converted into DNA through a process called reverse transcription, which is facilitated by the enzyme reverse transcriptase.

5. **Symptoms and Transmission**: Polio primarily affects the spinal cord, leading to symptoms such as paralysis and weakness, particularly in younger children. The virus is transmitted through contaminated water and food.

6. **Conclusion**: Based on the information gathered, it can be concluded that polio is caused by the poliovirus, which is an RNA virus.

### Final Answer:
Polio is caused by the poliovirus, which is a single-stranded RNA virus.

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