Cholera is caused by _________.

Explanation

**Step-by-Step Solution:**

1. **Identify the Disease**: The question asks about the cause of cholera. Cholera is a disease that affects the digestive system.

2. **Understand Microorganisms**: Cholera is caused by microorganisms, which are tiny organisms that cannot be seen with the naked eye. They include various types such as viruses, bacteria, and fungi.

3. **Focus on Bacteria**: Among the microorganisms, bacteria are known to cause various diseases, including cholera.

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