DETROIT - General Motor's (NYSE: GM) Chevrolet, Buick, GMC and Cadillac brands sold 272,512 vehicles in the United States in July 2015, a 6 percent increase and the four brands' best combined July since 2007.
What is the relationship between 'GMC' and 'DETROIT' in the context of the input sentence.
Options: headquarters location, creator, distributed by, stock exchange