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').

Acoustic guitars come in ____ types.\Question: Choose the right answer from options given a) two b) ten c) one d) four
a

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

Mice become sexually mature in just a couple months and produce about ____ litters in one year.\Question: Choose the right answer from options given a) ten b) eight c) three d) two

b