Final answer:
Vaccines administered intramuscularly are typically given in the deltoid muscle of the upper arm.
Step-by-step explanation:
The correct answer is a) Deltoid muscle. Vaccines administered intramuscularly are typically given in the deltoid muscle of the upper arm. This location is preferred because it has a large muscle mass and is easily accessible. The deltoid muscle is located on the lateral side of the upper arm, between the shoulder and the elbow.