Which Statement About Vaccines Is Correct

Which statement about vaccines is correct?

A) Vaccines will always cause the patient to become ill in order to build the immune system.
B) Vaccines never cause the patient to become ill in order to build the immune system.
C) Vaccines are not intended to cause the patient to become ill in order to build the immune system.
D) Vaccines need to be administered on a continuous basis in order to be effective.
E) It is only necessary to be vaccinated once in order to have immunity for your entire life.