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: Food waste is transformed into soil-like humus in ____ to seven days.\Question: Choose the right answer from options given a) ten b) five c) zero d) three

Output: d


Input: Consider Input: Marriage is the legal union of ____ people.\Question: Choose the right answer from options given a) one b) no c) five d) two

Output: d


Input: Consider Input: Xenon has ____ valence electrons.\Question: Choose the right answer from options given a) four b) one c) eight d) zero


Output: c