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: Lisa's mom promised her a new bike if she got all A's. She worked harder than ever. When she got her report card, she had four As and one B plus. She was so disappointed she wouldn't be getting her bike. Her mom was still proud of her grades, so she got it anyway.
 selected sentence: Lisa's mom promised her a new bike if she got all A's.

Lisa works harder >Causes/Enables> Lisa's mom promised a new bike