_____ Cause(s)mild and Limited Disease,whereas _____ Cause(s)more Severe Disease and Higher

Multiple Choice

_____ cause(s) mild and limited disease,whereas _____ cause(s) more severe disease and higher mortality.

A) Antigenic drift; antigenic shift
B) Antigenic shift; antigenic drift
C) Epidemics; pandemics
D) Pandemics; epidemics.