What is the relationship between Viacom and CBS in the context of the input sentence. Choose an answer from: 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.

CBS did not disclose details of the agreement, but it comes just days after its sister company Viacom Inc threatened to pull its cable channels from Time Warner's 13 million homes because of a disagreement over a separate deal.

Answer: parent_organization