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').

[Q]: Atoms are extremely small, on the order of a few ____ billionths of a meter.\Question: Choose the right answer from options given a) ten b) seven c) nine d) eight
[A]: a


[Q]: Females reach sexual maturity around ____ to five year-olds.\Question: Choose the right answer from options given a) four b) five c) one d) ten
[A]: a


[Q]: Coyotes breed each winter and give birth in the spring to substantial litters of four to ____ pups.\Question: Choose the right answer from options given a) two b) seven c) six d) no
[A]:
c