Given the task definition, example input & output, solve the new input case.
Given a passage and a question, find the answer to the question based on the passage. The answer should consist of only one word that lies in the span of only one of the sentences in the passage.
Example: Paragraph: Nix v. Hedden , 149 U.S. 304 ( 1893 ) , was a decision by the Supreme Court of the United States that , under U.S. customs regulations , the tomato should be classified as a vegetable rather than a fruit . The Court 's unanimous opinion held that the Tariff Act of 1883 used the ordinary meaning of the words `` fruit '' and `` vegetable , '' instead of the technical botanical meaning .
Question: is tomato a fruit or vegetable us supreme court

Output: vegetable
The answer 'vegetable' is correct as it lies in the sentence - "Nix v. Hedden , 149 U.S. 304 ( 1893 ) , was a decision by the Supreme Court of the United States that , under U.S. customs regulations , the tomato should be classified as a vegetable rather than a fruit ", which is a part of the passage.

New input case for you: Paragraph: The NSO is conducted on two levels each year . It was the first Olympiad to be conducted by SOF.It has been conducted since 1996 . Students from class I - XII may participate in the examination .
Question: how many levels are there in science olympiad

Output:
two