TASK DEFINITION: In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.
PROBLEM: What's the name for earth's supply of water?

SOLUTION: hydrosphere

PROBLEM: Who plays garrett on i didn't do it?

SOLUTION: Peyton Clark

PROBLEM: How many episodes are on season 3 of empire?

SOLUTION:
18