Final answer:
The EMT operating the AED is responsible for calling "clear" before administering a shock to ensure safety and effectiveness during a cardiac emergency.
Step-by-step explanation:
When using an Automated External Defibrillator (AED), the person responsible for calling to "clear" the patient before delivering a shock is the EMT operating the defibrillator. It is crucial that no one is touching the patient when the shock is delivered to prevent the transmission of the electrical charge to anyone other than the patient. The AED's automated prompts aid both laypersons and professionals during a cardiac emergency, guiding users through the process and ensuring that CPR is administered when necessary before the device analyzes the heart's rhythm and advises whether a shock is needed.