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.

[Q]: Who played keyboard on the beatles rooftop concert?
[A]: Billy Preston


[Q]: In 550 bc which leader began the persian empire?
[A]: Cyrus II of Persia


[Q]: Saint martin is part of what larger group of islands?
[A]:
Leeward Islands, Lesser Antilles, West Indies islands