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.
Analyze the relationship between 'GMC' and 'DETROIT' within the context of the input sentence.
Options: creator, headquarters location, stock exchange, distributed by