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]: Bulls can stand as tall as ____ feet at the shoulders.\Question: Choose the right answer from options given a) one b) five c) seven d) four
[EX A]: b

[EX Q]: 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
[EX A]: c

[EX Q]: All insects have heads, abdomens, and thoraxes, antennae, ____ legs, and wings.\Question: Choose the right answer from options given a) six b) ten c) zero d) seven
[EX A]:
a