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: Many tortoises can retract their head, their ____ limbs and tail into the shell for protection.\Question: Choose the right answer from options given a) no b) one c) two d) four
Example Output: d

Example Input: Black bears stand ____ to six feet long and almost three feet at the shoulders when on all fours.\Question: Choose the right answer from options given a) three b) five c) four d) one
Example Output: b

Example Input: Monocots have one cotyledon and dicots have ____ cotyledons.\Question: Choose the right answer from options given a) one b) two c) ten d) six
Example Output:
b