In this task, you need to provide the correct option for a given problem from the provided options.

Ex Input:
Problem: find the number of different prime factors of 441 
Options: a ) 4 , b ) 2 , c ) 3 , d ) 5 , e ) 6

Ex Output:
b


Ex Input:
Problem: 20 balls are numbered 1 to 20 . a ball is drawn and then another ball is drawn without replacement . what is the probability that both balls have even numbers ? 
Options: a ) 7 / 30 , b ) 3 / 14 , c ) 9 / 38 , d ) 4 / 21 , e ) 5 / 26

Ex Output:
c


Ex Input:
Problem: jo ' s collection contains us , indian and british stamps . if the ratio of us to indian stamps is 7 to 2 and the ratio of indian to british stamps is 5 to 1 , what is the ratio of us to british stamps ? 
Options: a ) 5 : 1 , b ) 10 : 5 , c ) 15 : 2 , d ) 20 : 2 , e ) 35 : 2

Ex Output:

e