Which item is a pathogen type that appears in the six listed types?

• A. Bacteria
• B. Rickettsiae
• C. Prions
• D. Fungi

Answer: (C)

Prions are infectious proteins that contain no genetic material and have no cellular structure, making them a distinct type of pathogen. In common classifications of infectious agents, six broad groups are bacteria, viruses, fungi, protozoa, helminths, and prions. Rickettsiae are bacteria, so they don’t represent a separate category from the others. Among the options, prions fit as the noncellular, protein-based pathogen that completes the six-category scheme, which is why they are the correct choice.