Explanation: Because is the only word that fits here and is gramatically correct in the first place, neverminding the fact that it says "Best Completes" <em>Because</em> is the only word that is gramatically correct in this situation.
The conjuction that best completes the sentence is Because, the other ones does not make sense in the fact that you wouldn´t say which katalina´s suitcase was left in or so that, or whereas, the only conjuction that makes sense in the way that the sentence is being written would be Because.
