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').

Input: Consider Input: Background radiation comes from ____ sources.\Question: Choose the right answer from options given a) zero b) three c) four d) no

Output: b


Input: Consider Input: Most roots require from ____ to six weeks to dry sufficiently to be safe.\Question: Choose the right answer from options given a) two b) four c) eight d) three

Output: d


Input: Consider Input: Platelets have a short life-span of just ____ days .\Question: Choose the right answer from options given a) one b) seven c) six d) five


Output: d