Viacom (NasdaqGS: VIAB - news ) fell 7.5 percent, 21st Century Fox lost 7.0 percent, CBS shed 4.6 percent and Comcast dropped 4.7 percent.
What is the relationship between 'Viacom' and 'CBS' in the context of the input sentence.
Options: chairperson, employer, parent organization, founded by