Which of the following is a type of respirator that supplies air to the user?

A supplied air respirator is designed to deliver clean air directly to the user from a separate source, typically through a hose connected to a stationary supply such as a compressor or air tank. This type of respirator is particularly useful in environments where the air is contaminated or lacks sufficient oxygen, as it ensures that users have a continuous flow of breathable air.

In contrast, an air purifying respirator relies on filters to remove contaminants from the air, rather than supplying fresh air. A self-contained breathing apparatus includes a tank of compressed air and is worn by the user, but it is not the same as a supplied air respirator since the air source is self-contained within the unit itself. A portable air filtration system does not provide air directly to the user; it cleans the ambient air instead. Thus, the chosen answer accurately describes a type of respirator that supplies air directly to the user, highlighting its importance in ensuring safety in hazardous environments.