Answer:
a. Taking the train into Boston, Katie reviewed the meeting minutes.
Step-by-step explanation:
This is the best way to rewrite this sentence in order to avoid the problem of the dangling modifier. A dangling modifier is a word or a phrase within a sentence that modifies a word that is not clearly stated. In this case, the original sentence makes it sound as if the meeting minutes were the ones taking the train into Boston. The reviewed sentence gets rid of this confusion.