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').
--------
Question: Centrifugal pumps can usually handle up to about ____ percent by volume of air.\Question: Choose the right answer from options given a) one b) five c) eight d) seven

Answer: b


Question: Cats have ____ sets of vocal cords.\Question: Choose the right answer from options given a) zero b) nine c) two d) three

Answer: c


Question: Allopatric speciation takes place when ____ populations are geographically isolated.\Question: Choose the right answer from options given a) four b) two c) three d) nine

Answer:
b