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').

Example Input: Today there are ____ federal states, each based on cultural affiliations.\Question: Choose the right answer from options given a) one b) nine c) seven d) zero
Example Output: b

Example Input: Lung disease is America's number three killer, responsible for ____ in seven deaths.\Question: Choose the right answer from options given a) five b) nine c) one d) four
Example Output: c

Example Input: Theobroma oil can exist in ____ different polymorphic forms of which only one is stable.\Question: Choose the right answer from options given a) two b) five c) four d) no
Example Output:
c