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: All mass spectrometers consist of ____ distinct regions.\Question: Choose the right answer from options given a) three b) one c) two d) zero
Example Output: a

Example Input: Teething begins for most babies around ____ to six months.\Question: Choose the right answer from options given a) three b) four c) five d) seven
Example Output: b

Example Input: Baseball is a team game played by ____ individuals.\Question: Choose the right answer from options given a) no b) zero c) four d) nine
Example Output:
d