Teacher:In this task, you need to provide the correct option for a given problem on probability from the provided options.
Teacher: Now, understand the problem? Solve this instance: Problem: a bag contains 3 red , 5 yellow and 4 green balls . 3 balls are drawn randomly . what is the probability that the balls drawn contain balls of different colours ? 
Options: a ) 2 / 7 , b ) 3 / 5 , c ) 3 / 11 , d ) 1 / 4 , e ) 7 / 16
Student:
c