‘Cholera’ is caused by

The correct option is Bacteria.

Cholera is an acute diarrheal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae.
Here is a step-by-step explanation of why this is the correct answer:

1. Causative Agent: Cholera is caused by a specific gram-negative, comma-shaped bacterium named Vibrio cholerae. It is not caused by viruses, fungi, or protozoans.
2. Mechanism of Disease: Once ingested, the bacteria colonize the small intestine and produce a potent toxin called cholera toxin. This toxin causes the mucosal cells of the intestine to secrete massive amounts of water and electrolytes, leading to severe watery diarrhea and dehydration.
3. Transmission: The bacteria are typically transmitted through the fecal-oral route, usually via contaminated drinking water or food that has been improperly handled.