Instructions: In this task, you need to provide the correct option for a given problem from the provided options.
Input: Problem: 100 liters of a mixture contains milk and water in the ratio 4 : 1 . if 10 liters of this mixture be replaced by 10 liters of milk , the ratio of milk to water in the new mixture would be ? 
Options: a ) 7 : 5 , b ) 9 : 2 , c ) 6 : 1 , d ) 5 : 4 , e ) 11 : 4
Output:
b