For f(x)= 4x+1 and g(x) = x^2 -5, find (f g)(x).
O A. 4x2 -19
O B. 4x3 + x2 - 4x -6
O C. 4x3 + x2 - 20x-5
O D. 4x3 + x2 - 5x -5