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.

When did nigeria become a federation of 19 states?
1976

Who sings hawaiian version of over the rainbow?
Israel Kaʻanoʻi Kamakawiwoʻole

What is the highest category hurricane to hit north carolina?

Category 4