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]: Sound waves travel through the air in a similar manner, but in all ____ dimensions.\Question: Choose the right answer from options given a) three b) five c) nine d) one
[EX A]: a

[EX Q]: All birds have ____ legs with four toes each.\Question: Choose the right answer from options given a) zero b) one c) three d) two
[EX A]: d

[EX Q]: Electric motors use current to set up ____ magnetic fields.\Question: Choose the right answer from options given a) two b) three c) ten d) one
[EX A]:
a