Which of the following is true of vaccinations?
a) vaccinations are used to treat existing disease symptoms.
b) vaccinations prevent the spread of communicable diseases.
c) vaccinations are only given after the disease has been cured.
d) vaccinations prevent the spread of noncommunicable diseases.

for anyone that's still wondering its B

(google the term herd immunity if your curious as to why but in short:

the resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination.) oh and non communicable diseases are ones that cant spread, communicable diseases are ones that can.

c genetic engineering