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: Double price is based on two golfers sharing ____ room.\Question: Choose the right answer from options given a) one b) zero c) six d) nine
Example Output: a

Example Input: National immunization vaccinates all children under ____ against polio.\Question: Choose the right answer from options given a) zero b) four c) ten d) five
Example Output: b

Example Input: Fawns weigh about ____ to nine pounds at birth.\Question: Choose the right answer from options given a) five b) ten c) nine d) six
Example Output:
d