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: Cats have ____ lives.\Question: Choose the right answer from options given a) five b) one c) two d) nine
Example Output: d

Example Input: Serial transfer is the sequential transmission of the ____ bit-voltages that constitute a byte.\Question: Choose the right answer from options given a) ten b) eight c) two d) four
Example Output: b

Example Input: Sprouts are ready for eating in three to ____ days.\Question: Choose the right answer from options given a) five b) seven c) six d) two
Example Output:
c