Under what condition may alcoholic beverages be served to passengers aboard an aircraft?

The correct choice regarding the conditions under which alcoholic beverages may be served to passengers aboard an aircraft is particularly focused on ensuring the safety and well-being of all individuals on board. Serving alcohol is subject to regulations aimed at preventing undue risk by ensuring that passengers do not pose a threat to others while consuming alcoholic beverages.

In this context, the most relevant factor is that alcoholic beverages should not be served to a passenger who is armed. This measure is in place to maintain safety, as the presence of weapons increases the stakes in managing intoxication levels and overall cabin behavior. Allowing alcohol to be served to a passenger who is armed could lead to dangerous situations if that individual becomes impaired.

Other options do not align with the specific regulations regarding alcohol service. For instance, the requirement of all passengers being seated or waiting until the cabin crew is ready does not directly address safety concerns in the same way. Similarly, the duration of the flight does not dictate whether alcohol can be served; rather, it is about ensuring that the consumption does not lead to impaired judgment or behavior that could endanger crew and passengers alike.