Definition: In this task, you will be given a short story. One sentence from the story is chosen. Consider the events that happen before that sentence, or are likely to have happened before it. Does any of them directly cause it, or simply make it possible? You should write your answer in the form " A >causes/enables> B". Try to use phrases and sentences from the story to compose your answer when possible.
Input: story: Allen was out one night doing some Christmas shopping. He thought he saw his friend off in the distance. He decided to sneak up and scare him. He crept up and grabbed his friend from behind. Allen felt terrible when he realized he'd grabbed a stranger.
 selected sentence: Allen felt terrible when he realized he'd grabbed a stranger.

Allen grabs a stranger >Causes/Enables> Allen realizes he grabbed