C knows the answer by deducing D is not yelling out the answer. + |# s3 z2 ?$ O6 H Q. q, oThat means D is not sure the answer by seeing one white and one black. + H: s/ M8 `5 }. ?www3.tvboxnow.comC 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.