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: 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

Output: b


Input: Consider Input: Prairie dogs bear four or ____ young per litter.\Question: Choose the right answer from options given a) five b) eight c) two d) zero

Output: a


Input: Consider Input: Most healthy men experience about three to ____ erections in their sleep each night.\Question: Choose the right answer from options given a) eight b) no c) zero d) five


Output: d