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]: Vision disorders affect ____ in every four school-age children.\Question: Choose the right answer from options given a) nine b) one c) five d) six
[EX A]: b

[EX Q]: Malignant tumors are more dangerous, and survival times can range from ____ months to several years.\Question: Choose the right answer from options given a) one b) no c) ten d) six
[EX A]: d

[EX Q]: Most children start to get their adult teeth at about ____ years of age.\Question: Choose the right answer from options given a) four b) six c) three d) seven
[EX A]:
b