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').

Metals often crystallize in a ____ dimensional version of the hexagonal closest packed structure.\Question: Choose the right answer from options given a) one b) seven c) three d) eight
c

Infants can tell their mothers from other mothers in ____ days.\Question: Choose the right answer from options given a) no b) zero c) five d) three
d

Grasshoppers develop through five to ____ instars.\Question: Choose the right answer from options given a) two b) six c) five d) three

b