The disease caused by a protozoan and spread by an insect is _________.

Options

A. dengue
B. malaria
C. polio
D. measles

Answer

**Step-by-Step Solution:**

1. **Identify the Type of Organism**: The question asks for a disease caused by a protozoan. Protozoans are single-celled organisms that can cause various diseases in humans.

2. **Consider the Mode of Transmission**: The disease must be spread by an insect. This means we need to think of diseases that are transmitted through insect bites.

3. **Evaluate the Given Options**: The options provided in the video include dengue, malaria, polio, and measles. We need to analyze each one to determine which fits the criteria of being caused by a protozoan and spread by an insect.

4. **Analyze Each Disease**:
- **Dengue**: Caused by a virus and spread by mosquitoes. Not a protozoan.
- **Malaria**: Caused by the protozoan *Plasmodium vivax* and spread by the bite of infected mosquitoes. This fits the criteria.
- **Polio**: Caused by a virus (poliovirus) and not spread by insects. Not a protozoan.
- **Measles**: Caused by a virus (morbillivirus) and not spread by insects. Not a protozoan.

5. **Conclusion**: The only disease that is caused by a protozoan and spread by an insect is malaria.

**Final Answer**: The disease caused by a protozoan and spread by an insect is **Malaria**.

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