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: Stroke is the number ____ cause of death in the United States.\Question: Choose the right answer from options given a) ten b) nine c) one d) three
Example Output: d

Example Input: Scorpions can live for ____ to seven years.\Question: Choose the right answer from options given a) one b) six c) five d) three
Example Output: d

Example Input: Some parachutes can take at least ____ days to pack.\Question: Choose the right answer from options given a) seven b) two c) no d) one
Example Output:
b