C knows the answer by deducing D is not yelling out the answer. ; i* G# J3 u8 {% q5 b! H9 t公仔箱論壇That means D is not sure the answer by seeing one white and one black.os.tvboxnow.com3 [: Q5 T2 `) m5 I
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.