Utilize the input text as a context reference, choose the right relationship between 'Halliburton' and 'HOUSTON' from the options.
Options: stock exchange, distributed by, headquarters location, creator

HOUSTON Aug 7 (Reuters) - Business is so tough for oilfield giants Schlumberger NV and Halliburton Co that they have come up with a new sales pitch for crude producers halting work in the worst downturn in years.
headquarters location