Do meningitis cases decline more rapidly postvaccination in the group vaccinated before age 19 or the group vaccinated after age 20?
Choose one:
A. The length of time between vaccination and decline in meningitis cases is shorter in the population vaccinated after age 20.
B. There is no correlation between the meningitis vaccine and a decline in the number of cases of meningitis.
C. The length of time between vaccination and decline in meningitis cases is shorter in the population vaccinated before age 19.
D. The length of time between vaccination and decline in meningitis cases is the same in the population vaccinated before age 19 and the population vaccinated after age 20.