Which of the Following Statements About Radio as an Advertising

Which of the following statements about radio as an advertising medium is true?

A) Almost 50 percent of all radio revenue comes from network advertising.
B) Radio has evolved into a primarily local advertising medium.
C) Radio advertising revenue has been steadily declining for the last 20 years.
D) One of the main weaknesses of radio as an advertising medium is the high production costs.
E) The high costs of radio advertising result in lower reach and frequency.