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: Beavers live in families that include an adult pair and ____ to three years worth of offspring.\Question: Choose the right answer from options given a) no b) one c) four d) ten
Example Output: b

Example Input: Lizards generally have ____ legs and movable eyelids.\Question: Choose the right answer from options given a) four b) two c) five d) zero
Example Output: a

Example Input: Perennial grass takes ____ to five years before it is mature enough to produce adequate seed.\Question: Choose the right answer from options given a) six b) zero c) three d) no
Example Output:
c