Definition: In this task you are given a story and a question regarding that story. You must judge whether the question is answerable based on the info given to you. Label the instances as "Answerable" or "Not Answerable" based on your judgment. the story and the question are separated by a new line character.
Input: Tony needed to buy his grandma a birthday present. He went to her favorite bakery. They were sold out of her favorite cake. The owner told Tony how to make it himself. His elated grandma couldn't tell the difference!
Why did Tony need to buy his grandma a birthday present?

Not Answerable