Official Explanation
Split #1: the famous missing verb mistake. The sentence begins with a subordinate clause starting with the word "while", and that has a bonafide noun + verb structure, as it should, but we need a main subject and main verb for the sentence. The "drought" is the main subject, and this needs a bonafide verb, "limited", not just the participle, "limiting." Choice (E) is incorrect.
Split #2: the structure "summer, Allport Corporation's biggest season" is correct: this is an appositive phrase. The structure " summer, which is Allport Corporation's biggest season" is grammatically correct, but a bit wordier.
Split #3: in saying, "summer, typically Allport Corporation's biggest season," we are saying that a typical pattern is that, of the four seasons, summer is the most lucrative. This is the meaning intended, the meaning given in the prompt. Saying " summer, Allport Corporation's biggest typical season" implies that Allport has typical seasons and untypical seasons, and among the typical seasons, summer is the biggest: this changes the meaning to one that makes far less sense, so this structure is wrong. Choice (B) & (D) are wrong.
Split #4: the word "only." Exactly what do we want to limit with the word "only"? Clearly, what is limited is "only $300 million" --- presumably, Allport was expecting to earn more than this. It makes no sense to put the word "only" before the verb "limited" or the direct object "total revenue": the structure "only limited" implies that the drought could have done more to the total revenue beyond merely limiting it, and the structure "only total revenue" implies that something else was limited besides total revenue. Both of those placements change the meaning from the one implied in the prompt to something nonsensical, so choice (B) & (C) & (E) are incorrect.
The only possible answer here is (A).