What piece of equipment can be assembled quickly to assist with rescue breathing?

The correct choice is a CPR mask, which is designed for immediate use in performing rescue breathing. This piece of equipment is compact, easy to carry, and can be quickly deployed in emergency situations. It allows the rescuer to deliver breaths to a person in respiratory distress while minimizing the risk of disease transmission. The mask typically includes a one-way valve that prevents the exhaled air from going back to the rescuer, making it an effective tool for providing emergency care.

Other equipment like AED pads and oxygen tanks serve different purposes in medical emergencies. AED pads are used for defibrillation when someone is in cardiac arrest, while oxygen tanks provide supplemental oxygen but are not specifically for rescue breathing. An Ambu bag, or bag-valve-mask system, is a more complex device used to provide positive pressure ventilation, but it requires more time to set up and may not be as quickly accessible as a simple CPR mask in urgent scenarios.