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').

Motor neurons are divided into ____ groups.\Question: Choose the right answer from options given a) two b) six c) seven d) eight
a

Cows have four stomachs, and the first ____ yield merchantable tripe.\Question: Choose the right answer from options given a) two b) five c) zero d) three
d

Guillemots are fed sprats ____ or four times a day and are constantly checked by vets.\Question: Choose the right answer from options given a) zero b) no c) three d) two

c