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').

Example 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
Example Output: d

Example 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
Example Output: b

Example Input: Cancer is blamed for nearly one in ____ deaths in the state, according to public health statistics.\Question: Choose the right answer from options given a) two b) six c) three d) four
Example Output:
d