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:
Traditional neon electrifies the inert gas from ____ directions.\Question: Choose the right answer from options given a) two b) nine c) one d) six

Ex Output:
a


Ex Input:
Heat pumps give off ____ fumes or harmful products of combustion.\Question: Choose the right answer from options given a) four b) zero c) six d) no

Ex Output:
d


Ex Input:
Hierarchical directories are also connective structures in ____ dimensions.\Question: Choose the right answer from options given a) eight b) three c) two d) ten

Ex Output:

c