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: Asthma accounts for ____ in six of all pediatric emergency visits in the United States.\Question: Choose the right answer from options given a) four b) seven c) one d) six
Example Output: c

Example Input: Marriage is the legal union of ____ people.\Question: Choose the right answer from options given a) one b) no c) five d) two
Example Output: d

Example Input: Many luminous shrimps are known but ____ luminous crabs .\Question: Choose the right answer from options given a) no b) four c) eight d) zero
Example Output:
a