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: Worker bees have ____ pairs of wax glands on the underside of their abdomens.\Question: Choose the right answer from options given a) no b) two c) nine d) four
Example Output: d

Example Input: Digital bandwidth enables signal to be condensed as a five to ____ ratio.\Question: Choose the right answer from options given a) one b) nine c) seven d) six
Example Output: a

Example Input: Viremia begins after ____ days and persists until fever abates.\Question: Choose the right answer from options given a) seven b) six c) three d) two
Example Output:
b