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

[Q]: Problem: a certain hobby shop sold model cars for $ 5.00 each and model trains for $ 8.00 each . if a customer purchased both cars and trains from the store for a total of $ 31.00 , what total number of cars and trains did the customer purchase ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7
[A]: c


[Q]: Problem: the number of people who purchased book a is twice the number of people who purchased book b . the number of people who purchased both books a and b is 500 , which is twice the number of people who purchased only book b . what is the number of people b who purchased only book a ? 
Options: a ) 250 , b ) 500 , c ) 750 , d ) 1000 , e ) 1500
[A]: d


[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
[A]:
c