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

Ex Input:
Problem: if log 1087.5 = 3.9421 , then the number of digits in ( 875 ) 10 is ? 
Options: a ) 30 , b ) 28 , c ) 27 , d ) 50 , e ) 25

Ex Output:
d


Ex Input:
Problem: a can contains a mixture of liquids a and b is the ratio 7 : 5 . when 3 litres of mixture are drawn off and the can is filled with b , the ratio of a and b becomes 7 : 9 . how many liter of liquid a was contained by the can initially ? 
Options: a ) 7 , b ) 10 , c ) 12 , d ) 14 , e ) 16

Ex Output:
a


Ex Input:
Problem: there are 2 available positions and 50 candidates , one half of whom are democrats and another half are republicans . if it was decided that the positions would be filled at random , then what is the probability r that the both positions will be taken by members of just one party ? 
Options: a ) 1 / 25 , b ) 12 / 49 , c ) 1 / 4 , d ) 24 / 49 , e ) 1 / 2

Ex Output:

d