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: Most bioluminescence is blue for ____ reasons.\Question: Choose the right answer from options given a) seven b) two c) four d) zero

Output: b


Input: Consider Input: Color codes are ____ digit combinations of letters and numbers that correspond to a specific color.\Question: Choose the right answer from options given a) six b) eight c) seven d) one

Output: a


Input: Consider Input: Natural ytterbium is a mixture of seven stable isotopes, with ____ other unstable isotopes known.\Question: Choose the right answer from options given a) seven b) zero c) eight d) three


Output: a