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: Turkish citizens can enter Bosnia and stay up to ____ months without a visa.\Question: Choose the right answer from options given a) five b) seven c) four d) three
Example Output: d

Example Input: Argentine ants are able to establish new colonies with as little as ____ worker ants and one queen.\Question: Choose the right answer from options given a) no b) two c) ten d) five
Example Output: c

Example Input: Mothers remain with their young for up to ____ months.\Question: Choose the right answer from options given a) seven b) six c) three d) zero
Example Output:
b