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: Astronomical observations suggest ____ or close to zero space-time curvature.\Question: Choose the right answer from options given a) six b) zero c) ten d) seven
Example Output: b

Example Input: Southern moles are six to ____ inches long and weigh three to four ounces.\Question: Choose the right answer from options given a) zero b) nine c) five d) seven
Example Output: d

Example Input: Banks hold no excess reserves, and the public holds ____ currency.\Question: Choose the right answer from options given a) no b) eight c) two d) six
Example Output:
a