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:
Ants have ____ stomachs.\Question: Choose the right answer from options given a) two b) nine c) four d) seven

Ex Output:
a

Ex Input:
Some people have ____ symptoms until the liver has been quite severely damaged.\Question: Choose the right answer from options given a) eight b) no c) nine d) ten

Ex Output:
b

Ex Input:
Frogs require from four to ____ years to reach maturity.\Question: Choose the right answer from options given a) nine b) eight c) five d) zero

Ex Output:
b