The term used to describe the speed and intensity with which a pathogen is likely to cause and infection is

Virulence

Explanation:

Virulence can be define as the ability of the microorganism or pathogen to infect and damage the host organism. It is the speed and intensity with which the pathogen infects the host. It can also be called as pathogenicity of the infecting organism. A virulent organism can be a bacteria, virus, protozoa or fungi. These organism can cause minor to severe infections.

no i don't feel that humans have oversubscribed some medications

i believe your answer would be c.. : )