Which of the Following Best Represents the Current Understanding of Immunization

Which of the following best represents the current understanding of immunization against diseases?

A) Immunizations should begin in infancy, continue through childhood, adolescence, and adulthood to be most effective.
B) Immunizations which begin at adolescence can provide the most effective protection.
C) Immunizations have improved greatly in the past decade and only need to occur in childhood.
D) Immunizations actually cause many diseases and should be avoided.