Given a sentence with a missing word, pick the answer option that best fills out the missing word in the sentence. Indicate each answer with its index ('a', 'b', 'c', 'd').

Q: Fever usually lasts for an average of ____ days in adults.\Question: Choose the right answer from options given a) zero b) three c) nine d) two

A: b
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Q: Scorpions can live for ____ to seven years.\Question: Choose the right answer from options given a) one b) six c) five d) three

A: d
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Q: Barbershop harmony is a style of unaccompanied singing with ____ voices harmonizing to the melody.\Question: Choose the right answer from options given a) two b) eight c) four d) three

A:
d
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