Isn't the answer A though. The lift is slowing down but its going upwards as it says top floor of the building. This means as particle is launched, it goes up so the vertical distance lowers and hence it stays in the air for a lower time (relative to when lift was stationary) and hence shorter...
What is the likelihood of the stimulus being really specific, such as an exact quote which we need to integrate or a picture which is obnoxious and the story has to be based on it?
Or is it more likely to get a question from the rubric such as confronting or unexpected discovery?