Utilize the input text as a context reference, choose the right relationship between Trulia and Zillow 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.

On integration progress Zillow CEO Spencer Rascoff insisted last quarter that successfully integrating Trulia would be his company's "top strategic priority for 2015."

Answer: parent_organization