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]: Big bluestem grows up to ____ feet tall.\Question: Choose the right answer from options given a) seven b) no c) nine d) eight
[EX A]: c

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

[EX Q]: Sows are hand-mated in groups with the breeding period restricted to ____ days for each group.\Question: Choose the right answer from options given a) seven b) zero c) no d) six
[EX A]:
a