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

Ex Input:
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

Ex Output:
a


Ex Input:
Problem: in a class of 87 students 41 are taking french , 22 are taking german . of the students taking french or german , 9 are taking both courses . how many students are not enrolled in either course ? 
Options: a ) 6 , b ) 15 , c ) 24 , d ) 33 , e ) 54

Ex Output:
d


Ex Input:
Problem: a certain bag contains 100 balls â € ” 20 white , 30 green , 10 yellow , 37 red , and 3 purple . if a ball is to be chosen at random , what is the probability that the ball will be neither red nor purple ? 
Options: a ) 0.9 , b ) 0.75 , c ) 0.6 , d ) 0.8 , e ) 0.5

Ex Output:

c