A nurse is administering the Haemophilus influenzae type B vaccine (Hib) to a 6-month-old infant. Which of the following actions should the nurse take?

A. Administer the vaccine in the vastus lateralis muscle using a 25-mm (1-in) needle: The vastus lateralis is the recommended intramuscular injection site for infants under 12 months. A 25-mm (1-inch) needle is appropriate for delivering the vaccine into the muscle tissue effectively. B. Administer the vaccine subcutaneously in the abdomen using a 16-mm (⅝-in) needle: The Hib vaccine should be administered intramuscularly, not subcutaneously. Subcutaneous injection in the abdomen is not a standard site for vaccines in infants. C. Administer the vaccine in the dorsogluteal muscle using a 51-mm (2-in) needle: The dorsogluteal site is avoided in infants due to the risk of sciatic nerve injury and poor muscle development at this age. This site is inappropriate for Hib vaccine administration. D. Administer the vaccine subcutaneously in the upper arm using a 13-mm (½-in) needle: The Hib vaccine requires intramuscular administration, and the subcutaneous route would not provide the proper immune response. The upper arm is also not ideal for infants this young.