How many quick don oxygen masks are available for the crew?

The correct answer indicates that there are four quick don oxygen masks available for the crew. This is an important aspect of crew resource management as it ensures that each crew member has immediate access to an oxygen supply in the event of a cabin depressurization. The availability of multiple masks is crucial for maintaining safety and ensuring the efficiency of emergency procedures. Each mask is designed for rapid deployment, allowing crew members to don them quickly and provide necessary oxygen for breathing, which is vital to mitigate hypoxia during emergencies.

While the other answer choices represent different numbers of masks, knowing that four quick don oxygen masks are available helps to ensure that sufficient oxygen equipment is on hand for crew members, promoting readiness and safety in potential critical situations. This understanding underscores the airline's commitment to crew safety and preparedness.