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: Sammy wanted a toy truck to play with. His mommy told him she would try to buy him one. On his birthday he got a cake, but no toy truck! He tried to act happy as he went upstairs to bed that night. Then he saw, on his bed, a brand new toy truck waiting for him!
 selected sentence: His mommy told him she would try to buy him one.

Sammy wants a toy truck >Causes/Enables> Sammy's mommy says she will try to buy him one