Which of the following is NOT a type of oxygen provided in the flight deck?

The choice of "Loft oxygen" is the correct answer as it is not a recognized type of oxygen provided in the flight deck. In the context of aviation, the other types of oxygen mentioned serve specific purposes.

Emergency oxygen is designed to be used during situations like rapid decompression, where crew and passengers may need immediate access to oxygen to ensure continued breathing at high altitudes. Supplemental oxygen is used to enhance the availability of oxygen in flight, particularly when flying at altitudes where the air pressure is lower, thus resulting in less oxygen available to breathe normally. First aid oxygen is available for administering to passengers or crew who may require medical assistance due to various health issues that require oxygen support.

In contrast, "Loft oxygen" does not correspond to any standard category of oxygen supply on the flight deck. This distinction makes loft oxygen an invalid option in the context of the question.