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: Control is defined as a dead plant with ____ signs of life.\Question: Choose the right answer from options given a) ten b) nine c) no d) zero
Example Output: c

Example Input: Carbon forms ____ bonds.\Question: Choose the right answer from options given a) five b) four c) two d) three
Example Output: b

Example Input: Risk factors can affect patients in ____ ways.\Question: Choose the right answer from options given a) five b) two c) zero d) no
Example Output:
b