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 Input:
Toucanets encompass ____ genera.\Question: Choose the right answer from options given a) seven b) six c) two d) one

Ex Output:
c


Ex Input:
All cattle have a ____ chambered stomach, consisting of a rumen, reticulum, omasum and abomasum.\Question: Choose the right answer from options given a) ten b) four c) six d) two

Ex Output:
b


Ex Input:
Stem cells form when an embryo is ____ days old, and go on to make up every part of the body.\Question: Choose the right answer from options given a) six b) seven c) no d) four

Ex Output:

d