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: When did the astros move to the american league?

SOLUTION: 2013

PROBLEM: When did arches national park become a national park?

SOLUTION: November 12, 1971

PROBLEM: When does new season of greys anatomy start 2017?

SOLUTION:
September 28, 2017