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: Poles CAN occur at ____ frequency.\Question: Choose the right answer from options given a) six b) four c) zero d) eight

A: c
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Q: Spores have ____ combinations of sexes.\Question: Choose the right answer from options given a) four b) five c) seven d) three

A: a
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Q: Most births produce a single offspring, but twins are born ____ out of every six or seven births.\Question: Choose the right answer from options given a) three b) four c) one d) zero

A:
c
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