Final answer:
The nurse should withhold the client's medication, Metoprolol, due to the client's heart rate of 48/min.
Step-by-step explanation:
The nurse should withhold the client's medication, Metoprolol, due to the client's heart rate of 48/min. Metoprolol is a beta blocker medication that works by blocking the beta-1 receptors in the heart, which slows down the heart rate. In this case, the client already has a heart rate of 48/min, which is already lowered, and administering Metoprolol can further decrease the heart rate to a dangerously low level.