19. A cube with an edge length of 3 inches is composed of 27 unit small cubes, of which, 21 are red small cubes and 6 are white small cubes. If the surface of the large cube is to have as few white cubes as possible, then the area of the white part on the surface of the large cube as a fraction of the total surface area of the large cube is ( ).
(A) $\frac{5}{54}$
(B) $\frac{1}{9}$
(C) $\frac{5}{27}$
(D) $\frac{2}{9}$
(E) $\frac{1}{3}$