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: Tardigrades are microscopic, water-dwelling, segmented animals with ____ legs.\Question: Choose the right answer from options given a) eight b) nine c) one d) seven
Example Output: a

Example Input: Astronomical observations suggest ____ or close to zero space-time curvature.\Question: Choose the right answer from options given a) six b) zero c) ten d) seven
Example Output: b

Example Input: Breast cancer strikes one out of every ____ American women.\Question: Choose the right answer from options given a) one b) nine c) no d) six
Example Output:
b