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:
Avian kidneys have ____ kinds of nephrons.\Question: Choose the right answer from options given a) four b) eight c) no d) two

Ex Output:
d


Ex Input:
Chlorine is manufactured in ____ ways.\Question: Choose the right answer from options given a) four b) two c) nine d) seven

Ex Output:
b


Ex Input:
Milk is a good source of ____ essential nutrients.\Question: Choose the right answer from options given a) six b) one c) eight d) nine

Ex Output:

d