TASK DEFINITION: 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.
PROBLEM: Who sang the original version of let it rain?

SOLUTION: Eric Clapton

PROBLEM: In what movie did the song white christmas make its debut?

SOLUTION: Holiday Inn

PROBLEM: What type of stone is stonehenge made of?

SOLUTION:
bluestone and sarsen sandstone