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

Input: Consider Input: Problem: a jar contains 3 black , 3 white and 1 green balls . if you pick two balls at the same time , what ' s the probability that one ball is black and one is white ? 
Options: a ) 2 / 7 , b ) 5 / 7 , c ) 4 / 7 , d ) 3 / 7 , e ) 1 / 2

Output: d


Input: Consider Input: Problem: there are 22 students in a class . in how many different ways can a committee of 3 students be formed ? 
Options: a ) 1180 , b ) 1320 , c ) 1540 , d ) 1760 , e ) 1920

Output: c


Input: Consider Input: Problem: a man & his wife appear in an interview for 2 vacancies in the same post . the probability of husband ' s selection is 1 / 7 & the probability of wife ' s selection is 1 / 5 . what is the probability that only 1 of them is selected ? 
Options: a ) 1 / 3 , b ) 2 / 3 , c ) 2 / 7 , d ) 3 / 11 , e ) 4 / 5


Output: c