Answer the following question given this paragraph: 

Most protist diseases in humans are caused by animal-like protists, or protozoa. Protozoa make us sick when they become human parasites. Three examples of parasitic protozoa are described below.


Q: What make us sick when they become human parasites?

 Choices:

- detritus

- viruses

- larvae

- protozoa

A:
protozoa
