Why is it necessary to give the HPV vaccine in multiple doses?

A. The viral DNA used in the vaccine needs a long time to integrate into the host genome and elicit an immune response.
B. Vaccines for viruses must be given in multiple doses because the viral particles are not very immunogenic.
C. Three doses of the HPV vaccine are given to elicit both a humoral and a cell-mediated response.
D. DNA vaccines are not very stable; therefore, multiple doses must be given to ensure an immune response.