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: Decompression illness is a continuum from ____ symptoms or signs to severe multisystem involvement.\Question: Choose the right answer from options given a) nine b) three c) no d) one
Example Output: c

Example Input: Hurricanes weaken rapidly when passing over land surfaces for ____ reasons.\Question: Choose the right answer from options given a) two b) three c) nine d) zero
Example Output: b

Example Input: Fluorescent lights are three to ____ times more energy-efficient.\Question: Choose the right answer from options given a) one b) four c) no d) ten
Example Output:
b