Despite serving as a punching bag for media executives frustrated by mobile video, Nielsen is unlikely to be knocked from its perch as the industry standard for buying and selling advertising even as leading rivals  Rentrak ( RENT - Get Report ) and comScore ( SCOR - Get Report )  plan to merge.
Take context from the input text and decide on the accurate relationship between 'comScore' and 'Rentrak' from the options provided.
Options: founded by, platform, location of formation, owner of