What is f(g(x)) when f(x) = 5x + 3, and g(x) = 3x2 + 3?
A) f(g(x)) = 8x^2 + 6
B) f(g(x)) = 15x^2 + 18
C) f(g(x)) = 75x^2 + 90x + 30
D) f(g(x)) = 255x^2 + 270x + 84