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').

[EX Q]: Most people have ____ kidneys.\Question: Choose the right answer from options given a) two b) five c) seven d) six
[EX A]: a

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

[EX Q]: Screws provide at least ____ times the holding power of nails.\Question: Choose the right answer from options given a) one b) seven c) two d) six
[EX A]:
b