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').

Ex Input:
Granite occurs in ____ separate masses.\Question: Choose the right answer from options given a) two b) eight c) nine d) no

Ex Output:
a


Ex 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

Ex Output:
b


Ex Input:
Diploid cells have ____ complete sets of chromosomes.\Question: Choose the right answer from options given a) four b) two c) eight d) zero

Ex Output:

b