Final answer:
If a patient with a temporary pacemaker is experiencing a spike followed by a QRS complex on the bedside monitor, the nurse's best action would be to set the pacemaker to the synchronous mode.
Step-by-step explanation:
If a patient with a temporary pacemaker is experiencing a spike followed by a QRS complex on the bedside monitor, the nurse's best action would be to d. Set the pacemaker to the synchronous mode. This is because the spike followed by the QRS complex indicates that the pacemaker is functioning properly, and setting it to the synchronous mode will ensure that it is synchronized with the patient's natural heart rhythm.