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

Problem: a bag has 9 green balls and 23 pink balls . how many green balls should be added to the bag so that the ratio of green balls and pink balls in the bag becomes 1 : 1 ?
Options: a ) 10 , b ) 11 , c ) 12 , d ) 13 , e ) 14
e