Answer:
b. exogenous
Step-by-step explanation:
Exogenous variations are variations that occur in one independent variable that helps one predict one or more dependent variables in a model.
Endogenous variations on the other hand are values that are determined by other variables ( these controlling variables are exogenous variables).
So in this scenario one-time shocks to a time series from a distinctly external influence (exogenous variable), such as a sudden dip in consumer sales (endogenous variable) after a disruptive event.