Which city does the airport code CUN refer to?

The airport code CUN is specifically designated for Cancun, Mexico. Airport codes are typically derived from the name of the city or the airport's name itself, following the International Civil Aviation Organization (ICAO) or International Air Transport Association (IATA) conventions. In this case, CUN is a recognizable and widely accepted code in the travel and airline industry, making it easy for travelers to identify Cancun as a destination. The code is straightforward for those familiar with international travel, as Cancun is a popular tourist destination known for its beaches and resorts. The other options, while being real cities with their own airport codes, do not relate to CUN.