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: Potential energy is divided into ____ different types of energy.\Question: Choose the right answer from options given a) eight b) three c) zero d) two

Output: b

Input: Consider Input: Child care is provided for children ages six weeks through ____ years of age.\Question: Choose the right answer from options given a) seven b) four c) two d) three
Output: b