Question

question 13
the capability of a communicable disease agent to cause disease in a susceptible host is
infectivity
pathogenicity
indirect transmission
etiology

question 14
a pathogenic agent enters a susceptible host through a
reservoir
carrier
portal of exit
portal of entry

Explanation:

For Question 13, pathogenicity is the ability of a disease - causing agent to cause disease in a susceptible host. Infectivity is about the ability to spread, indirect transmission is a mode of spread, and etiology is the study of causes.
For Question 14, a pathogenic agent enters a susceptible host through a portal of entry. A reservoir is a source of the agent, a carrier can transmit it, and a portal of exit is how the agent leaves a host.

Answer:

Question 13: pathogenicity
Question 14: portal of entry