Utilize the input text as a context reference, choose the right relationship between 'Petrobras' and 'RIO DE JANEIRO' from the options.
Options: location of formation, member of, publisher, headquarters location

RIO DE JANEIRO Aug 28 Brazilian Senator Jose Serra said on Friday he expects a vote on changing the country's oil law to ease demands on state-run firm Petrobras and reduce local content rules to take place in September.
headquarters location