Which of the following is a critical step in using an AED?

Turning on the AED is a critical step when using the device, as it initiates the automated assessment of the patient's heart rhythm and prepares the machine to deliver a shock if necessary. Once the AED is powered on, it provides audio or visual prompts that guide the rescuer through the process of pad placement, heart rhythm analysis, and shock delivery if indicated. This step is essential because it ensures that the AED is ready to provide immediate assistance in the event of a cardiac emergency.

In contrast, attaching pads to the patient's clothing is not appropriate, as the pads must be placed directly on the patient's bare skin for effective contact and energy delivery. Checking for responsiveness is a crucial first action as well; however, once the AED is being utilized, the focus shifts to delivering care promptly. Leaving the pads in the box until needed delays the response further and does not assist the patient during a critical moment. Each of these actions must be executed in a specific order to maximize the effectiveness of the resuscitation efforts.