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

Problem: the ratio between the current age of a and b is 6 : 7 . if b is 4 years old than a . what will be the ratio of the ages of a and b after 4 years ? 
Options: a ) 7 : 8 , b ) 8 : 9 , c ) 4 : 6 , d ) 4 : 8 , e ) 5 : 8
a

Problem: a cat leaps 6 leaps for every 5 leaps of a dog , but 2 leaps of the dog are equal to 3 leaps of the cat . what is the ratio of the speed of the cat to that of the dog ? 
Options: a ) 4 : 5 , b ) 2 : 3 , c ) 4 : 1 , d ) 1 : 9 , e ) 3 : 2
a

Problem: find the highest common factor of 36 and 84 . 
Options: a ) 12 , b ) 10 , c ) 16 , d ) 19 , e ) 18

a