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

Example Input: Problem: a certain hobby shop sold model cars for $ 5.00 each and model trains for $ 8.00 each . if a customer purchased both cars and trains from the store for a total of $ 31.00 , what total number of cars and trains did the customer purchase ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7
Example Output: c

Example 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
Example Output: b

Example Input: Problem: a dog takes 5 leaps for every 6 leaps of a hare . if one leap of the dog is equal to 3 leaps of the hare , the ratio of the speed of the dog to that of the hare is : 
Options: a ) 1 : 6 , b ) 5 : 6 , c ) 6 : 1 , d ) 5 : 1 , e ) 9 : 1
Example Output:
d