Why Do Newspapers Typically Charge National Advertisers More for National

Why do newspapers typically charge national advertisers more for national ads than they charge local advertisers for local ads?

A) National advertisers typically demand an (run-of-paper) ROP schedule.
B) Newspapers incur additional costs in serving national advertisers.
C) National advertisers refuse to use a local or regional promotional schedule.
D) The Federal Trade Commission has decreed that discounts for interstate ad rates are illegal.
E) The reach for local ads is much higher than the reach for national ads.