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:
National immunization vaccinates all children under ____ against polio.\Question: Choose the right answer from options given a) zero b) four c) ten d) five

Ex Output:
b


Ex Input:
Oar boats are smaller than motor boats and can accommodate four to ____ people.\Question: Choose the right answer from options given a) zero b) three c) five d) no

Ex Output:
c


Ex Input:
Babies show an interest in solid foods when they are approximately four to ____ weeks old.\Question: Choose the right answer from options given a) nine b) eight c) five d) six

Ex Output:

c