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:
Government buildings fly flags of the ____ nations.\Question: Choose the right answer from options given a) ten b) no c) seven d) two

Ex Output:
d


Ex Input:
Parliaments can last five years, often last ____ and a bit.\Question: Choose the right answer from options given a) four b) three c) five d) two

Ex Output:
a


Ex Input:
Air layering is a technique invented by the Chinese ____ thousand years ago.\Question: Choose the right answer from options given a) two b) one c) four d) five

Ex Output:

c