C knows the answer by deducing D is not yelling out the answer. 8 @: }$ _% d5 G5 U0 p公仔箱論壇That means D is not sure the answer by seeing one white and one black. ) B6 l' C' G5 r( E) eC 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.