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:
Metals often crystallize in a ____ dimensional version of the hexagonal closest packed structure.\Question: Choose the right answer from options given a) one b) seven c) three d) eight

Ex Output:
c


Ex Input:
Elephants give birth to ____ calf every four to nine years on average.\Question: Choose the right answer from options given a) ten b) one c) eight d) six

Ex Output:
b


Ex Input:
Cosmetics come in ____ types, greasy and non-greasy.\Question: Choose the right answer from options given a) no b) one c) two d) six

Ex Output:

c