You will be given a definition of a task first, then some input of the task.
The task is about reading the given story and question, then finding an answer to the given question. Based on the passage provided and the given question, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

story: Once there was a group of adventurers who went on an adventure in a place named Hyperion where there was a lot of snow. Their names were Thor, Bravos, and Pierre. Thor and Bravos were from Norway, but Pierre was from Paris, France. Because of where he was from, he wasn't used to the cold. To stay warm, Pierre wore three jackets. One day during their adventure the men saw a strange cave. Thor and Bravos wanted to go inside, but Pierre was afraid. He had heard that a horrible bug monster named Vlastos lived in the caves of Hyperion. Thor and Bravos told him that was only a fairy tale. They told him the only thing he really needed to worry about was hitting his head on a rock in the cave. Finally they got Pierre to go into the cave. Inside there were lots of tunnels. They chose the middle tunnel. The tunnel went down into the earth. After a long time it ended. The men were in a huge room. There were beautiful ice shapes on the walls., question: What did they say he should really worry about?
Output:
hitting his head on a rock