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: Tetrapods are animals that have ____ legs or leg-like appendages.\Question: Choose the right answer from options given a) four b) one c) ten d) six

A: a
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Q: Avian kidneys have ____ kinds of nephrons.\Question: Choose the right answer from options given a) four b) eight c) no d) two

A: d
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Q: Batch growth is carried out in a finite volume of nutrients and is characterised by ____ phases.\Question: Choose the right answer from options given a) four b) three c) nine d) ten

A:
a
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