Identify the sentence which contains a coordinating connection. after we realized my sister had outgrown her running shoes, we drove to the shoe store. although she had purchased new running shoes two months before, her feet measured a full size bigger now. as a result, she decided to buy shoes which were a size and a half bigger than her old pair. she tried on several pairs, and she chose a blue and grey pair to replace her old shoes.

In my opinion, the correct answer is D. She tried on several pairs, and she chose a blue and grey pair to replace her old shoes.

There are exactly 7 coordinating conjunctions in English, and they can easily be remembered by the acronym FANBOYS: for, and, nor, but, or, yet, and so. In this case, we have two clauses ("She tried on several pairs", "and she chose a blue and grey pair to replace her old shoes"), connected with a conjunction "and".