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

Ex Input:
Problem: a certain telephone company offers two plans , a and b . under plan a , the company charges a total of $ 0.60 for the first 4 minutes of each call and $ 0.06 per minute thereafter . under plan b , the company charges $ 0.08 per minute of each call . what is the duration of a call , in minutes , for which the company charges the same amount under plan a and under plan b ? 
Options: a ) 2 , b ) 9 , c ) 15 , d ) 18 , e ) 30

Ex Output:
d


Ex Input:
Problem: a certain bag contains 60 balls — 22 white , 18 green , 5 yellow , 6 red , and 9 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 ) 0.09 , b ) 0.15 , c ) 0.54 , d ) 0.75 , e ) 0.91

Ex Output:
d


Ex Input:
Problem: a certain telephone company offers two plans , a and b . under plan a , the company charges a total of $ 0.60 for the first 5 minutes of each call and $ 0.06 per minute thereafter . under plan b , the company charges $ 0.08 per minute of each call . what is the duration of a call , in minutes , for which the company charges the same amount under plan a and under plan b ? 
Options: a ) 2 , b ) 9 , c ) 15 , d ) 21 , e ) 30

Ex Output:

c