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

[EX Q]: Problem: in a class total 34 students , 16 are have a brother , 15 are have sisters , 9 students do n ' t have either brothers or sisters . find the number of students having both brother and sisters . 
Options: a ) 4 , b ) 5 , c ) 6 , d ) 7 , e ) 8
[EX A]: c

[EX Q]: Problem: in what ratio must a grocer mix two varieties of pulses costing rs . 15 and rs . 20 per kg respectively so as to get a mixture worth rs . 16.50 per kg ? 
Options: a ) 3 : 7 , b ) 5 : 7 , c ) 7 : 3 , d ) 7 : 5 , e ) none
[EX A]: c

[EX Q]: Problem: in a group of 8 semifinalists , all but 2 will advance to the final round . if in the final round only the top 3 will be awarded medals , then how many groups of medal winners are possible ? 
Options: a ) 20 , b ) 56 , c ) 120 , d ) 560 , e ) 720
[EX A]:
b