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

Ex Input:
Problem: the ratio between speed of the two trains is 7 : 8 . if the 2 nd train runs 400 km in 4 hrs , what is the speed of the 1 st train ? 
Options: a ) 87.9 , b ) 87.5 , c ) 87.7 , d ) 87.6 , e ) 43.3

Ex Output:
b


Ex Input:
Problem: 9 log 9 ( 5 ) = ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 5 , e ) 8

Ex Output:
d


Ex Input:
Problem: the ratio of the present ages of two friends is 2 : 3 and 6 years back , the ratio was 1 : 3 . what will be the ratio of their ages after 4 years ? 
Options: a ) 1 : 4 , b ) 3 : 4 , c ) 1 : 2 , d ) 3 : 1 , e ) 3 : 2

Ex Output:

b