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.

What is wrong with april kepner's baby on grey's anatomy?
Osteogenesis Imperfecta type 2

When did arches national park become a national park?
November 12, 1971

Who played wong jack man in birth of the dragon?

Xia Yu