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]: Cows breed at ____ years, bulls at four.\Question: Choose the right answer from options given a) two b) three c) seven d) one
[EX A]: b

[EX Q]: Female elephants have babies about ____ years apart, and they have only one each time.\Question: Choose the right answer from options given a) eight b) one c) zero d) three
[EX A]: d

[EX Q]: Women now constitute over thirty ____ percent of the global work force.\Question: Choose the right answer from options given a) six b) zero c) three d) ten
[EX A]:
c