What is the relationship between Twitter and SAN FRANCISCO 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.

SAN FRANCISCO (Reuters) - Prime Minister Narendra Modi has documented his push to bring U.S. investments and jobs back to India on his Facebook and Twitter pages since landing in the United States this week, posting photos with the likes of former New York City Mayor Michael Bloomberg and group shots with Fortune 500 CEOs.

Answer: headquarters_location