Final answer:
The best site for an IM injection in a 15-month-old child is the vastus lateralis muscle, as it is large and has lower risks for nerve and blood vessel injury.
Step-by-step explanation:
The nurse selects the best site for giving an IM injection to a 15-month-old child, which is the vastus lateralis muscle. a) Deltoid b) Vastus lateralis c) Dorsogluteal d) Biceps femoris.
Explanation: For young children like a 15-month-old, the vastus lateralis muscle, which is located on the lateral aspect of the thigh, is considered the safest and most recommended site for intramuscular (IM) injections. This is due to its large muscle mass, away from major nerves and blood vessels, and low risk of injury.
The deltoid muscle is often too small in young children for IM injections, while the dorsogluteal site is not preferred due to its proximity to the sciatic nerve and significant fat content, which could reduce the efficacy of the medication absorption. The biceps femoris is also not a commonly used site for IM injections in infants and young children.