C knows the answer by deducing D is not yelling out the answer. 2 K$ ~. d# A2 g+ D1 ?2 `! ]" t公仔箱論壇That means D is not sure the answer by seeing one white and one black. 6 |; e* O G9 J0 R1 K- R公仔箱論壇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.