Utilize the input text as a context reference, choose the right relationship between Lyft and SAN FRANCISCO from the options. Options: 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) - The Massachusetts attorney general's office is examining how Uber and Lyft ensure equal access for people with disabilities, a spokeswoman for the attorney general told Reuters, adding to numerous other business issues facing the two companies.

Answer: headquarters_location