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]: Earthworms have ____ pairs of hearts.\Question: Choose the right answer from options given a) seven b) five c) one d) no
[EX A]: b

[EX Q]: Stroke is the number ____ cause of death in the United States.\Question: Choose the right answer from options given a) ten b) nine c) one d) three
[EX A]: d

[EX Q]: Cognitive changes are probably equivalent to about a ____ to six month delay in progression.\Question: Choose the right answer from options given a) one b) two c) three d) seven
[EX A]:
c