A Popular Comedy Show,which Is Shown on Fox Network,had a Rating

A popular comedy show,which is shown on Fox network,had a rating of 4.0 but a share of 7.Why are these two numbers different?

A) Rating includes all TV households, and share considers only those households that have their TVs on at that time.
B) Share includes all TV households, and rating considers only those households that have their TVs on at that time.
C) Rating is provided by Arbitron and share is provided by Nielsen, and both use different methods for estimating audience size.
D) Rating is provided by Nielsen and share is provided by Arbitron, and both use different methods for estimating audience size.
E) Rating compares audience size to the entire TV universe, while share compares only audience size to other network programming.