Utilize the input text as a context reference, choose the right relationship between 'Rubicon Project' and 'LOS ANGELES' from the options.
Options: employer, publisher, headquarters location, creator

LOS ANGELES & LONDON--(BUSINESSWIRE)-- Launch of Argentina and Hungary Advertising Co-Ops Expands Rubicon Project Leadership Role as The Exclusive Publisher Co-operative Marketplace Serving More Than 290 Premium Publishers Globally
headquarters location