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:
Many tortoises can retract their head, their ____ limbs and tail into the shell for protection.\Question: Choose the right answer from options given a) no b) one c) two d) four

Ex Output:
d


Ex Input:
Most people have ____ kidneys.\Question: Choose the right answer from options given a) two b) five c) seven d) six

Ex Output:
a


Ex Input:
Cubs stay with their mothers for two to ____ years.\Question: Choose the right answer from options given a) no b) nine c) eight d) three

Ex Output:

d