Question

which item must be passed from person to person in order to acquire an infectious disease?
o blood
saliva
o pathogen
o antigen

Explanation:

An infectious disease is caused by a pathogen (such as bacteria, viruses, fungi, or parasites). For a person to acquire an infectious disease, the pathogen must be transmitted from an infected person (or other source) to a susceptible person. Blood and saliva can be vehicles for pathogen transmission in some cases (e.g., certain viruses in blood - like HIV in some exposure scenarios, or some viruses in saliva - like Epstein - Barr virus in close contact), but they are not the essential element. An antigen is a molecule that can trigger an immune response, but it is not the agent that causes the disease (the pathogen is).

Answer:

pathogen