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.
Take context from the input text and decide on the accurate relationship between 'GMC' and 'DETROIT' from the options provided.
Options: distributed by, stock exchange, creator, headquarters location