Final answer:
The condition caused by parasitic organisms growing and multiplying on or within a host can be referred to as an infection, an infectious disease, or pathogenesis. Therefore, all the provided choices are correct in describing this condition.
Step-by-step explanation:
The condition in the host that results from pathogenic parasitic organisms growing and multiplying within or on the host is called an infection. This occurs when a microorganism enters the host and begins to multiply. However, not all infections lead to disease. An infectious disease is specifically an illness resulting from an infection that causes noticeable symptoms in the host. The process by which a pathogen causes disease is known as pathogenesis, and involves several stages: exposure, adhesion, invasion, and infection. When considering the options provided: 1) an infection, 2) an infectious disease, 3) pathogenesis, the most accurate answer is all of the choices are correct, as they are all related to the process by which pathogenic parasites affect their host.