This is also a great example of an idiom question. Notice how slightly changing the wording of an idiom can really affect the meaning:
When Bill arrived, it really AGGRAVATED the situation. --> When you use the word aggravate in this context, it is a verb and you don't need to use the preposition "TO" after it.
When Bill arrived, it WAS really AGGRAVATING to me. --> When you are saying something was or is aggravating (especially to a person), the verb in the sentence becomes the is/was and "aggravating" needs a "to" after it.
This would be another way to split these answers. It's always great to dissect these questions in multiple ways during practice!
Brett Beach-Kimball | Manhattan GMAT Instructor
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