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]: Uncontrolled diabetes can increase risk by up to ____ times.\Question: Choose the right answer from options given a) five b) four c) seven d) eight
[A]: b


[Q]: Natural tellurium consists of ____ isotopes.\Question: Choose the right answer from options given a) six b) seven c) eight d) one
[A]: c


[Q]: All children normally wake up ____ or five times each night after dreams.\Question: Choose the right answer from options given a) four b) no c) two d) six
[A]:
a