Choose the Item That Best Matches Each Item of the Following

Choose the item that best matches each item of the following:
-A numerical expression of the number of all existing cases of a disease or condition measured at a given period of time

A) Morbidity
B) Endemic
C) Epidemic
D) Pandemic
E) Validity
F) Index
G) Incidence
H) Epidemiology
I) Prevalence
J) Disease rates
K) Mortality
L) Causality
M) Etiology
N) Risk factors
O) Reliability
P) Surveillance