Hi ani781 and thanks for your question,
There are a few things to clarify in this sentence; we will examine every sentence and fetch what makes it wrong.
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.
We are talking about telly here. The author makes a claim and bolsters it with an example towards the end of the sentence. Generally, you would expect to see an example introduced by "such as", but here we stumble across a subordinate clause introduced by "as".
1. We do introduce examples with "such as", but "such as" should be followed by nouns, pronouns, and things that function as nouns, such as noun phrases and gerunds.
2. Let's get to "Each". "Each", if it is used as subject, wants to be followed by a singular verb. On the other hand, if "each" is not used as subject but follows the subject, then the nearest verb to the right of "each" should agree with the actual subject.
Example Given:
M. Each of the three major networks broadcasts. (subject=each-->singular verb)
R. The three major networks each broadcast. (subject=networks-->plural verb)
3. "If......, then....." / "If......, ......." is an expression used to highlight a cause-effect relationship. In this very sentence its use is inappropriate and unnecessary.
With this in mind, let's approach the answer choices.
(A) superficial such as when each of the three major networks.
Use of "such as" is inappropriate (1). "Each" should agree with a singular verb (2).
(B) superficial, as can sometimes occur if all of the three major networks
"can sometimes occur" is a filler, as Rich pointed out. The use of "if" is inappropriate (3).
(C) superficial if the three major networks all
meaning issue, the idea conveyed by this answer choice does not reflect at all the meaning expressed by the author. Moreover the use of "if" is wrong (3). All of a sudden the sentence feels like a cause-effect relationship.
(D) superficial whenever each of the three major networks
The use of "whenever" does not feel right. The author created an example, which can reflect either a real or invented situation. Using "whenever" feels as we are sure that the three major networks each broadcasted the same statement -and they did such thing more than once. Moreover "each" should be followed by a singular verb (1).
Hope it helps,
-tathastuGMAT