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:
What kind of rose is used to make rose water?

Ex Output:
Rosa × damascena


Ex Input:
When did nigeria become a federation of 19 states?

Ex Output:
1976


Ex Input:
Who used the first standardized system of measurement?

Ex Output:

ancient peoples of Egypt, Mesopotamia and the Indus Valley, and perhaps also Elam