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

[EX Q]: Problem: find the number of different prime factors of 25650 
Options: a ) 4 , b ) 2 , c ) 3 , d ) 5 , e ) 6
[EX A]: a

[EX Q]: Problem: of the 200 stamps in a collection , 90 are foreign and 60 are more than 10 years old . if 20 stamps are both foreign and more than 10 years old , how many stamps are neither foreign nor more than 10 years old ? 
Options: a ) 50 , b ) 70 , c ) 100 , d ) 130 , e ) 150
[EX A]: b

[EX Q]: Problem: a certain university will select 2 of 3 candidates eligible to fill a position in the mathematics department and 4 of 5 candidates eligible to fill 2 identical positions in the computer science department . if none of the candidates is eligible for a position in both departments , how many different sets of 3 candidates are there to fill the 3 positions ? 
Options: a ) 42 , b ) 10 , c ) 40 , d ) 65 , e ) 15
[EX A]:
e