再来一提,请教nn们

Although it claims to delve into political issues, television can be superficail such as when each of the three major networks broadcast exactly the same statement from a political candidate.

a superficial such as when each of the three major networks

b superficial, as can sometimes occour if all of the three major networks

c superficial if the three major networks all

e superficial whenever each of the three major networks

f superficial, as when the three major networks each

答案是e, 请nn们指点

 the three major networks each,   the subject is  the three major networks but not "each"

C is nothing wrong in Grammar, but its meaning is changed by useing "if"; Moreover, "superficial if the three major networks all" is a questionable phrase.  "all the three major networks" is much better than C.

thus, F, superficial, as when the three major networks each,  is the best.

居然有F, where is this sentence from??