While the marketing department projected robust sales throughout the

Dear Shyam123123,
I'm happy to respond. Here's the question again. Just so you know, if you follow the link posted with the question, you will find a full text explanation of the question.

Here's the question again:
While the marketing department projected robust sales throughout the summer, typically Allport Corporation’s biggest season, the drought in Midwestern states limited total revenue to only $300 million in the third quarter.
(A) typically Allport Corporation’s biggest season, the drought in Midwestern states limited total revenue to only
(B) Allport Corporation’s biggest typical season, the drought in Midwestern states limited only total revenue to
(C) which typically is Allport Corporation’s biggest season, the drought in Midwestern states only limited total revenue to
(D) which is typically Allport Corporation’s biggest season, the drought in Midwestern states limiting total revenue to only
(E) Allport Corporation’s biggest typical season, the drought in Midwestern states only limiting total revenue to

Think about version (D).
While the marketing department projected robust sales throughout the summer, which is typically Allport Corporation’s biggest season, the drought in Midwestern states limiting total revenue to only only $300 million in the third quarter.
Think about the design of that entire sentence:
"While the marketing department projected robust sales throughout the summer" = subordinate clause
"which is typically Allport Corporation’s biggest season" = noun modifier for "summer"
"the drought in Midwestern states limiting total revenue to only only $300 million in the third quarter" = absolute phrase
Now, here's the real paradox. Each one of those three pieces is grammatically and logically perfect. We have a perfect subordinate clause, a perfect noun modifier clause (a relative clause), and a perfect absolute phrase. All great. The problem is: we don't have an independent clause. We don't have a main subject and a main verb, and every sentence needs this. As it stands, version (D) is not a complete sentence! In version (D), we have tossed together a combination of grammatically correct parts, but the part that we really need is not there! This is why (D) is wrong. For more information, see:
https://magoosh.com/gmat/2012/gmat-gramm ... b-mistake/

That's what is tricky about version (D). You see, when you do GMAT SC, you have to "look small" and "look big" at the same time. Some of the splits in this sentence are small details: for example, the placement of the word "only" or the "typical"/"typically" split. Version (D) gets all the small details correct, but unfortunate, at the "big" level, at the level of a full sentence, (D) doesn't work because it's not a complete sentence: it lacks the main subject and main verb that every sentence needs. No single part of if is incorrect by itself, but the whole is incorrect, because the mistake is not what is present but what is absent. In moral theology, folks sometimes talk about the difference between "sins of commission" (those bad things I actively do) vs. "sins of omission" (the times I do something bad by not taking action, by my silence or my avoidance). It's like this with GMAT SC. Sometimes the mistake is what appears in the sentence, and sometimes, everything that appears is mistake free, but the mistake is what is missing. The problem in (D) is a "sin of omission."

Does all this make sense?
Mike