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: Some motors contain ____ gears and spin very fast, and have little if any torque.\Question: Choose the right answer from options given a) four b) three c) five d) no
Example Output: d

Example Input: Blister beetles have ____ instars and overwinter as mature larvae in the soil.\Question: Choose the right answer from options given a) eight b) seven c) no d) six
Example Output:
b