This is an oft discussed question. Search and you'll get a bucket full of discussions.

Here's one -
https://www.manhattangmat.com/forums/alt ... t2074.html

pradeepkaushal9518 wrote:plz explain the rule here

Although it claims to delve into political issues, television can be superficial 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 occur if all of the three major networks
(C) superficial if the three major networks all
(D) superficial whenever each of the three major networks
(E) superficial, as when the three major networks each

The issues:

1. Each:


Each + NOUN ----ALWAYS Singular.
Plural NOUN + Each----ALWAYS Plural.

==> Since the verb is "broadcast", we should have a subject of the verb "broadcast" as plural.
-->This kills A and D.
2. If -then:

If X happens, Y will happen.

--> it means that if something happens, another one will also happens.

Now, think about the options B and C.

If all three major networks broadcast the same statements, TV will be superficial.---Is it always correct? NO.

So, B and C changes the meaning of the sentence.

Answer MUST be E.