What is the abbreviation for O'Hare International Airport?

O'Hare International Airport is designated the airport code ORD, which is derived from the name of its original location, Orchard Field. The use of three-letter airport codes is standardized by the International Civil Aviation Organization (ICAO) and the International Air Transport Association (IATA) to provide a unique identification for airports around the world. ORD has been in use for many years and is recognized globally by airlines, travelers, and in aviation operations, making it the correct choice. The other options listed do not correspond to the established airport code for O'Hare and may not represent any existing airports.