C knows the answer by deducing D is not yelling out the answer., w: {* E/ i$ z% g8 b
That means D is not sure the answer by seeing one white and one black.www.tvboxnow.com; d( e2 a: r- p* D2 w) c: t/ _
C saw B is wearing the white, hence he is wearing the black
C, because he saw B's hat is white and he knows D can see the color of B's and his hat. If B and his hat has the same color, D would speak out. But D kept silent, so C knows that his hat's color must be different.