Which scenario demonstrates appropriate use of an automated external defibrillator (AED)?

The appropriate use of an automated external defibrillator (AED) involves scenarios where a patient is experiencing a cardiac emergency, specifically pulseless ventricular fibrillation or pulseless ventricular tachycardia. In this context, using an AED on a pregnant woman is appropriate. This is because during cardiac arrest, both the mother and the fetus suffer from the lack of oxygenated blood, and timely defibrillation can increase the chances of survival for both.

When it comes to using an AED on an unconscious adult or a child aged 6, it is important to ensure that they also do not have a pulse and are in a state of cardiac arrest. In scenarios where an AED is used on someone who does have a pulse, as indicated in the other scenarios, it would be inappropriate and possibly harmful to administer defibrillation, as the device is specifically designed for use in arrhythmias where no pulse is detected.

Thus, the correct answer highlights a scenario where the AED can be effectively used while considering the unique circumstances of the situation.