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:
Uncontrolled diabetes can increase risk by up to ____ times.\Question: Choose the right answer from options given a) five b) four c) seven d) eight

Ex Output:
b

Ex Input:
Some infected horses show ____ signs and become chronic carriers of the disease.\Question: Choose the right answer from options given a) nine b) six c) four d) no

Ex Output:
d

Ex Input:
Many children have febrile seizures before the age of ____ without developing epilepsy.\Question: Choose the right answer from options given a) nine b) one c) five d) eight

Ex Output:
c