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 won rookie of the year nba 2004?
[EX A]: LeBron James

[EX Q]: Who beat one direction to win x factor?
[EX A]: Matt Cardle

[EX Q]: Which is an example of a renewable energy source?
[EX A]:
geothermal heat