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]: 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]: Scientists divide bats into ____ groups.\Question: Choose the right answer from options given a) five b) two c) one d) zero
[EX A]: b

[EX Q]: Indoor polo uses three players, and outdoor has ____ per team.\Question: Choose the right answer from options given a) three b) four c) eight d) nine
[EX A]:
b