Utilize the input text as a context reference, choose the right relationship between comScore and Rentrak 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.

And unlike Nielsen, an independent measurement company, comScore and Rentrak have an advertising giant as a significant shareholder: WPP PLC.

Answer: owner_of