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.
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Question: Which unit is used to measure mass in the metric system?

Answer: kilogramme


Question: Who plays gabe on when calls the heart?

Answer: Mitchell Kummen


Question: When did blackpool tower circus stop using animals?

Answer:
1990