C knows the answer by deducing D is not yelling out the answer.tvb now,tvbnow,bttvb P' I0 E6 N. z( R, O! s
That means D is not sure the answer by seeing one white and one black.* I5 U6 @2 j8 I3 s" o
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.