For the given functions f and g. find fog and state its domain fX)= X + / ; g(X) = V/3x + 21 A. (f - g)(x) (x x2 - 7. X=0 X Bx + 21 O B. (-9)()= (x(x = =7, x=0) 2 O C. (f - 9)(x) = (x x =0) X 3 /x + 7 DD. (f -9)(x) X {xx = -7, x=0}