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: Mammals have only ____ sets of teeth.\Question: Choose the right answer from options given a) six b) five c) seven d) two

A: d
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Q: Most viruses have only ____ organelles.\Question: Choose the right answer from options given a) ten b) two c) four d) eight

A: b
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Q: Japan has ____ main islands running from north to south.\Question: Choose the right answer from options given a) four b) two c) five d) one

A:
a
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