The parent of a newborn asks a nurse why, except for hepatitis B vaccine, the immunization schedule does not start until the infant is 2 months old. How should the nurse respond?a. 'A newborn's spleen can't produce efficient antibodies.'b. 'Infants younger than 2 months are rarely exposed to infectious disease.'c. 'The immunization will attack the infant's immature immune system and cause the disease.' d. 'Maternal antibodies interfere with the development of active antibodies by the infant when immunized.'