If f(x) = 3x^2 + 4 and g(x) = 2x - 1, what is f(g (x))?

A) 12x^2 - 12x + 7
B) 3x^2 + 2x + 3
C) 12x^2 - 4x + 5
D) 36x^2 - 36x + 9