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: Unsafe acts cause ____ times as many accidents as unsafe conditions.\Question: Choose the right answer from options given a) no b) eight c) one d) four
Example Output: d

Example Input: All baleen whales have ____ blow holes.\Question: Choose the right answer from options given a) zero b) four c) seven d) two
Example Output: d

Example Input: Some botanists recognise ____ botanical varieties.\Question: Choose the right answer from options given a) zero b) two c) four d) no
Example Output:
b