What is United Airlines' policy regarding alcohol service on flights?

United Airlines has a clear policy regarding the service of alcohol on its flights, which aligns with legal regulations and industry standards. Alcohol can be served to passengers aged 21 and older, reflecting compliance with the minimum legal drinking age in the United States. This policy ensures the responsible service of alcohol by requiring monitored consumption, which is important for maintaining passenger safety and comfort during the flight.

Offering alcohol only to those of legal drinking age not only adheres to legal statutes but also ensures that the airline is practicing responsible liquor service, which is essential for the wellbeing of all passengers aboard. The aspect of monitored consumption helps flight attendants manage the situation, ensuring that alcohol is consumed in moderation.

The other options do not accurately reflect United Airlines' policy: all passengers being served alcohol regardless of age does not comply with the legal age restrictions; the notion that only flight attendants can consume alcohol onboard contrasts with the service principles that allow passengers to enjoy beverages; and while there are indeed protocols around alcohol service during takeoff and landing, the key point here is the age restriction and monitored service, which are foundational elements of the airline's approach to alcohol service.