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: Carbon can bond to a maximum of ____ atoms.\Question: Choose the right answer from options given a) six b) ten c) five d) four

Output: d


Input: Consider Input: Respiratory therapists complete ____ to four years of education.\Question: Choose the right answer from options given a) one b) nine c) zero d) two

Output: d


Input: Consider Input: Acupuncture is a traditional Chinese therapy which originated over ____ thousand years ago.\Question: Choose the right answer from options given a) one b) three c) five d) eight


Output: c