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: Ed tossed a bag of chips into his backpack before he walked to school. He then put in his textbooks and notebooks. At lunch he opened his bag to get his chips. The books had crushed all of Ed's chips. Ed had to eat the destroyed chips for lunch.
 selected sentence: At lunch he opened his bag to get his chips.

Ed packs a bag of chips before lunch at school >Causes/Enables> Ed opens the bag of chips at lunch