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.

Example Input: Who played boo radley in the movie to kill a mockingbird?
Example Output: Robert Selden Duvall

Example Input: Who is pyramid head in silent hill movie?
Example Output: Roberto Campanella

Example Input: What is the formula of the hydride formed by rubidium?
Example Output:
RbH