Question

what is the first link on the chain of infection?
○ reservoir
○ portal of entry
○ pathogen
○ host

Explanation:

The chain of infection starts with the pathogen (the infectious agent) as the first link. A pathogen is a microorganism (like bacteria, virus, fungus) that can cause disease. Reservoir is where the pathogen lives, portal of entry is how it enters a new host, and host is the organism that gets infected, but the first link is the pathogen itself.

Answer:

C. Pathogen