Which statement best defines a pathogen in the context of foodborne illness?

Only bacteria that grow on food and produce visible spoilage and unpleasant smell.

Any nonliving particle or chemical contaminant in food that alters flavor but does not cause disease.

A macroscopic organism like a rodent or insect that physically contaminates food by contact, but not a microorganism.

A microorganism (such as a bacterium, virus, or parasite) that can cause disease when transmitted by food or water.