Find the minimum value of the function for the polygonal convex set determined by the given system of inequalities:
2x+2y ≤ 16
-2x+6y < 24
-4x+4y > -8
f(x,y)=5x+4y
A. The minimum is at (3,5)
B. The minimum is at (5,3)
C. The minimum is at (9,7)
D. The minimum is at (8,0)