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: Millie enjoyed playing peek-a-boo. One day, she saw a little boy in the car next to her. She started playing peek-a-boo with him. He waved, and started playing peek-a-boo too! Millie's excitement about her new friend lasted until nap time.
 selected sentence: He waved, and started playing peek-a-boo too!

Millie played peek-a-boo with a baby >Causes/Enables> The baby waved to Millie