Take context from the input text and decide on the accurate relationship between 'Buick LaCrosse' and 'Buick' from the options provided.
Options: stock exchange, brand, parent organization, currency

The expansion covers the 2005 Buick LaCrosse and the 2007 Pontiac Grand Prix in the U.S., as well as the 2005 Buick Allure in Canada.
brand