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:
Matter exists in ____ forms, solid, fluid and plasma.\Question: Choose the right answer from options given a) ten b) nine c) three d) five

Ex Output:
c


Ex Input:
TriMetal Irons Discover the benefits of ____ different metals.\Question: Choose the right answer from options given a) five b) seven c) no d) three

Ex Output:
d


Ex Input:
Scientists say that earthly life has been around nearly ____ billion years.\Question: Choose the right answer from options given a) four b) one c) ten d) two

Ex Output:

a