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 Input:
Are radio waves electromagnetic waves or sound waves?

Ex Output:
electromagnetic waves


Ex Input:
The proof of having paid the road toll for swiss highways is called?

Ex Output:
Vignette


Ex Input:
Who did lowell hire to work in his factory?

Ex Output:

Lowell mill girls