TOEFL Listening: TPO-TOEFL阅读TPO - U87I1D1I74CIT38QN$

In paragraph 5, commercial radio programming is best described as the result of A. a financially successful development that enabled large telecommunications firms to weaken their competition. B. the desire of electronics and telecommunications companies to make sound technology profitable C. a major development in the broadcasting industry that occurred before the 1920s D. the cooperation between telecommunications companies and the motion picture industry