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: I once wanted to have a pet frog. A purple frog would be the perfect pet. My friends laughed and said that frogs cannot be purple. I looked in several books and found out there really are purple frogs. I enjoyed telling my friends that they were wrong.
 selected sentence: My friends laughed and said that frogs cannot be purple.

I wanted a purple pet frog >Causes/Enables> My friends laughed at me