Final answer:
The primary purpose of an AED is to restore normal heart rhythm during a cardiac arrest by delivering an electrical shock to correct abnormal heart rhythms like ventricular fibrillation.
Step-by-step explanation:
The primary purpose of an Automated External Defibrillator (AED) during a cardiac arrest is b) To restore normal heart rhythm. An AED delivers a large charge in a short burst, or a shock, to a person's heart to correct abnormal heart rhythms, such as cardiac or ventricular fibrillation. By applying this shock, the defibrillator can terminate the arrhythmia and enable the body's natural pacemaker to resume a normal rhythm, which is essential for the heart to pump blood effectively. It's vital to follow up with CPR, as recommended, until emergency services arrive or the patient regains consciousness.