In the context of the input sentence, determine the relationship between 'Zillow' and 'SEATTLE'.
Options: distribution format, headquarters location, creator, chief executive officer

SEATTLE and VANCOUVER, British Columbia, Sept. 24, 2015 /PRNewswire/ -- Retsly®, a software company that collects and standardizes real estate data from multiple listing services (MLSs) and more than 3,000 counties announced today that it's holding a hackathon, called zip.code, November 6 – 8, 2015, at the Zillow Group office in San Francisco, Calif. Zip.code will bring together hundreds of developers to create new products and services using MLS and public records data to benefit agents, brokers, and MLSs.
headquarters location