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: A boy hear a siren outside the house. He ran outside to see what it was. In the distance a fire truck drove towards him. He waved at the firemen as they passed. One of the firemen waved back at the boy.
 selected sentence: A boy hear a siren outside the house.

A fire truck drives by >Causes/Enables> A boy hears a siren