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

Ex Input:
Problem: in a college , the ratio of the number of boys to girls is 8 : 5 . if there are 300 girls , the total number of students in the college is 
Options: a ) 420 , b ) 520 , c ) 620 , d ) 780 , e ) 820

Ex Output:
d


Ex Input:
Problem: the ratio between the present ages of a and b is 4 : 3 respectively . the ratio between a ' s age 4 years ago and b ' s age 4 years hence is 1 : 1 . what is the ratio between a ' s age 4 years hence and b ' s age 4 years ago ? 
Options: a ) 3 : 4 , b ) 3 : 0 , c ) 3 : 1 , d ) 3 : 2 , e ) 9 : 5

Ex Output:
e


Ex Input:
Problem: 30 liters of a mixture contains milk and water in the ratio 2 : 1 . if 5 liters of this mixture be replaced by 5 liters of milk , the ratio of milk to water in the new mixture would be ? 
Options: a ) 3 : 2 , b ) 3 : 1 , c ) 4 : 1 , d ) 5 : 2 , e ) 2 : 1

Ex Output:

d