Explanation:

Here’s the breakdown:

- Filariasis: This one’s caused by thread-like worms (nematodes), not protozoa. It spreads through mosquito bites and leads to swelling, typically in legs.

- Mumps: Definitely not protozoan. Mumps is a viral disease—think fever, swollen salivary glands, and sometimes complications in adults.

- Amoebic dysentery: You picked this. It’s caused by the protozoan parasite *Entamoeba histolytica*. Main symptoms are diarrhea, sometimes with blood and mucus. This one’s all about contaminated water or food.

- Anthrax: Caused by *Bacillus anthracis*, which is a bacterium. Usually affects livestock, but humans can get it too—definitely not protozoan.

So, amoebic dysentery is the only protozoan disease in this list. Good eye!