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: Butterflies have ____ stages in their life cycle.\Question: Choose the right answer from options given a) two b) four c) no d) eight
Example Output: b

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: Grilled foods can contain ____ groups of carcinogenic compounds.\Question: Choose the right answer from options given a) two b) four c) no d) seven
Example Output:
a