Which airport code represents Manchester, United Kingdom?

The airport code that represents Manchester, United Kingdom, is MAN. This code is derived from the name of the city itself, with "MAN" serving as an abbreviation that is both easy to remember and aligns with the International Civil Aviation Organization (ICAO) norms for airport codes.

In this instance, 'MAN' successfully identifies Manchester Airport, which is the primary airport serving the city and its surrounding metropolitan area. This airport plays a crucial role in international and domestic air travel.

Understanding airport codes is important for travel planning, logistics, and navigation, as they provide a quick reference for the location of flights and airports. The other options provided relate to different cities: MEX represents Mexico City, MFA does not exist as a commonly recognized code, and MIA represents Miami.