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').

Input: Consider Input: Ozone is a molecule containing ____ oxygen atoms.\Question: Choose the right answer from options given a) one b) nine c) no d) three

Output: d


Input: Consider Input: Circles mark the approximate locations of ____ recently discovered solar systems.\Question: Choose the right answer from options given a) four b) no c) zero d) nine

Output: a


Input: Consider Input: Pigeons are sexually mature at about ____ months of age.\Question: Choose the right answer from options given a) no b) six c) eight d) four


Output: b