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:
Mothers typically have from one to ____ cubs, which are born blind and toothless.\Question: Choose the right answer from options given a) six b) zero c) four d) seven

Ex Output:
a

Ex Input:
Statistics show that within ____ years of divorce, many people marry a second time.\Question: Choose the right answer from options given a) four b) nine c) six d) three

Ex Output:
d

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