Final answer:
The 2nd rescuer's task is to apply AED pads and follow the AED's prompts while the first rescuer continues chest compressions. This procedure is critical in dealing with ventricular fibrillation or related conditions during a cardiac emergency.
Step-by-step explanation:
When acting as the 2nd rescuer and you have an AED available, the next best task after your partner has performed compressions for two minutes is A - Apply the AED pads and wait for the AED prompts. It's important to minimize the interruption in chest compressions, and while one rescuer is performing compressions, the other should apply the AED pads to the patient's chest. Once the AED is set up and ready, it will provide prompts on when to stand clear and deliver a shock if it's necessary. Early defibrillation is crucial in the case of ventricular fibrillation or pulseless ventricular tachycardia, as it can increase the chances of survival. Time is of the essence in such emergencies and the AED can guide rescuers through the process with verbal instructions.