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: Big bluestem grows up to ____ feet tall.\Question: Choose the right answer from options given a) seven b) no c) nine d) eight

A: c
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Q: Twin souls are the last ____ souls to individualize.\Question: Choose the right answer from options given a) two b) ten c) zero d) six

A: a
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Q: Influenza viruses undergo ____ types of changes.\Question: Choose the right answer from options given a) five b) ten c) two d) zero

A:
c
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