Which of the Following Statements About the Length of Television

Which of the following statements about the length of television commercials is true?

A) Commercials have become longer as the demand for broadcast time has dwindled.
B) Commercial length is increasing and 60-second spots are typically considered the norm.
C) Commercials became shorter because advertisers turned to shorter spots as a way of controlling their media costs.
D) Commercial length is increasing as the cost of ad space decreases.
E) The number of 60-second commercials has declined due to the networks' desire to sell more ads and restrict clutter.