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]: Decapod crustaceans have ____ pairs of limbs.\Question: Choose the right answer from options given a) five b) four c) six d) seven
[EX A]: a

[EX Q]: Diarrheal disease kills ____ million children every year.\Question: Choose the right answer from options given a) three b) no c) four d) ten
[EX A]: a

[EX Q]: College students are ____ times more likely to become infected than healthy adults.\Question: Choose the right answer from options given a) three b) six c) five d) eight
[EX A]:
c