Which type of oxygen system incorporates a rebreather bag-type mask?

The correct choice is the continuous flow system, which utilizes a rebreather bag-type mask. This type of system is designed to provide a steady stream of oxygen to the user while allowing the exhaled breath to be collected in the rebreather bag. The bag creates a reservoir of oxygen that can be reused on the next inhalation, which enhances the efficiency of oxygen delivery and supports prolonged usage.

In a continuous flow system, the oxygen is delivered at a constant rate, ensuring that there is always oxygen available for inhalation regardless of the user's breathing pattern. The rebreather bag is particularly effective in lowering the risk of hypoxia when supplemental oxygen is needed, especially at higher altitudes or in emergency situations.

Other systems mentioned, like demand flow and high-pressure systems, do not utilize a rebreather bag. Demand flow systems provide oxygen on an as-needed basis, activating only when the user inhales. Meanwhile, high-pressure and liquid oxygen systems serve different functions related to storage and delivery but do not functionally incorporate a rebreather mechanism in the manner specified in this question.