Which of the following is typically used as a power source for WAGD systems?

The correct answer is medical air, as it serves as the primary power source for Waste Anesthetic Gas Disposal (WAGD) systems. These systems are designed to safely remove and dispose of anesthetic gases that may escape into the environment during medical procedures. Medical air, which is specifically filtered and compressed air used in healthcare settings, is suitable for this purpose because it is readily available, safe, and compatible with the equipment used in respiratory care and anesthetic gas management.

In comparison, the other options do not provide the necessary features for effective operation of WAGD systems. Natural gas is primarily used as a fuel for heating and cooking and is not safe or appropriate for use in medical ventilation systems. Liquid oxygen, while sometimes used in medical settings, is utilized to provide supplemental oxygen and not as a power source for gas disposal systems. Carbon monoxide is a toxic gas that poses serious health risks and would not be acceptable in any medical gas system designed to ensure patient safety and environmental compliance.