The number of musicians employed to play accompaniment for radio and television commercials has sharply decreased over the past ten years. This has occurred even though the number of commercials produced each year has not significantly changed for the last ten years.

Which of the following, if it occurred during the past ten years, would contribute LEAST to an explanation of the facts above?

(A) The type of music most popular for use in commercials has changed from a type that requires a large number of instruments to a type that requires very few instruments.

(B) There has been an increase in the number of commercials that use only the spoken word and sound effects, rather than musical accompaniment.

(C) There has been an increase in the number of commercials that use a synthesizer, an instrument on which one musician can reproduce the sound of many musicians playing together.

(D) There has been an increase in the number of commercials that use prerecorded music as their only source of music.（E）

(E) There has been an increase in the number of commercials that use musicians just starting in the music industry rather than musicians experienced in accompanying commercials.

D中的prerecord为什么就减少了m的人数呢？pre不也是需要他们来录吗？