Which airport code corresponds to Gulfport, Mississippi?

The airport code that corresponds to Gulfport, Mississippi, is GPT. In the context of aviation, airport codes are unique three-letter identifiers assigned to each airport. These codes often bear some relation to the name of the city or airport they represent. For Gulfport, GPT is derived from the city's name, making it easy to associate the code with the location.

The other options reference different airports: GRB is the code for Green Bay, Wisconsin; FNT corresponds to Flint, Michigan; and FSD stands for Sioux Falls, South Dakota. Each of these codes is distinct, reflecting different locations and cannot be associated with Gulfport, Mississippi. Thus, GPT is the correct choice as it accurately identifies Gulfport's airport.