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: Ocular dryness responds to the use of artificial tears applied every ____ to three hours.\Question: Choose the right answer from options given a) no b) one c) three d) eight

Output: b


Input: Consider Input: Living cells have at least ____ parts.\Question: Choose the right answer from options given a) seven b) three c) zero d) four

Output: b


Input: Consider Input: Human beings are the being that bridges the ____ worlds.\Question: Choose the right answer from options given a) seven b) two c) four d) nine


Output: b