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.

[EX Q]: Who owns the treasure island in las vegas?
[EX A]: Phil Ruffin

[EX Q]: What's the name for earth's supply of water?
[EX A]: hydrosphere

[EX Q]: The active form of vitamin d also known as a hormone is called?
[EX A]:
calcitriol