What is the relationship between GMC and DETROIT in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

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.

Answer: headquarters_location