Which term best defines the instinct for the body to defend itself

a) stress

b) compulsion

c) resistance

d) distress

The term that best defines the instinct for the body to defend itself is C) Resistance

To figure this out, it'll be easiest to come up with the definition of each word to match which definition fits best with the question.

Stress : a state of mental or emotional strain or tension
Compulsion : the state of forcing or being forced to do something
Resistance : the refusal to accept or comply with something; the attempt to prevent something by action or argument.
Distress : extreme anxiety, sorrow, or pain.

Based on these definitions, the definition of resistance fit most because when your body is defending yourself, it is ATTEMPTING TO PREVENT a sickness/disease.