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: Some homeopathic remedies are so dilute, ____ molecules of the healing substance remain.\Question: Choose the right answer from options given a) ten b) three c) one d) no
Example Output: d

Example Input: All butterflies go through ____ life stages .\Question: Choose the right answer from options given a) one b) four c) zero d) five
Example Output: b

Example Input: Sets are of ____ kinds, finite and infinite.\Question: Choose the right answer from options given a) three b) eight c) no d) two
Example Output:
d