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]: 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]: Respiratory therapists complete ____ to four years of education.\Question: Choose the right answer from options given a) one b) nine c) zero d) two
[EX A]: d

[EX Q]: Most people change careers four to ____ times during the course of their life's work.\Question: Choose the right answer from options given a) six b) nine c) seven d) five
[EX A]:
c