In 1990, a 30-Second Ad During the Super Bowl Cost

In 1990, a 30-second ad during the Super Bowl cost $700,000. By 2014, the cost had soared to $4 million for a 30-second spot. The most likely reason for the escalating cost is that

A) the number of TV viewers for the Super Bowl since 1990 has grown substantially.
B) the ads are much more elaborate and therefore more expensive to produce.
C) the NFL knows advertisers will pay anything it wants.
D) the ad agencies have dramatically increased their creative and production fees.
E) the companies that create Super Bowl ads do not have to run any other ads all year long.