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]: Ground squirrels breed once a year, averaging ____ to eight per litter.\Question: Choose the right answer from options given a) seven b) one c) six d) ten
[A]: a


[Q]: Today there are ____ basic classifications of sausage.\Question: Choose the right answer from options given a) five b) four c) six d) one
[A]: a


[Q]: Many comets have ____ tails.\Question: Choose the right answer from options given a) two b) six c) three d) one
[A]:
a