To use the supplemental oxygen with mask retainers on the CRJ 700, what should be pulled to start the oxygen flow?

To initiate the flow of supplemental oxygen using the mask retainers on the CRJ 700, it is essential to pull the streamer. The streamer is specifically designed to activate the release of oxygen when pulled, ensuring that the oxygen flows properly to the user. This mechanical action connects the oxygen flow system, allowing the user to access the supplemental oxygen necessary for maintaining adequate oxygenation in the event of cabin depressurization or other emergencies.

The other options do not facilitate the activation of the oxygen supply. For instance, pulling the mask retainer would not trigger the oxygen flow, as it is intended to help hold the mask in place rather than activate oxygen delivery. The oxygen tank itself is part of the system providing oxygen but does not have a direct role in starting the flow when using the masks. Lastly, the face mask is the interface through which oxygen is delivered but, similar to the mask retainer, does not initiate the flow. Therefore, understanding the function of the streamer is critical in using the supplemental oxygen system effectively during emergency situations.