Final answer:
Bacteria, fungus, and protozoa are considered living disease-causing agents.
Step-by-step explanation:
The disease-causing agents that are considered living (biotic) things are bacteria, fungus, and protozoa. Bacteria are one-celled organisms without a nucleus, and some types of bacteria can cause diseases in humans. Fungi are multicellular organisms that can cause diseases such as athlete's foot and fungal infections. Protozoa are single-celled organisms that can cause diseases like malaria and amoebic dysentery.