C knows the answer by deducing D is not yelling out the answer.公仔箱論壇8 `/ n7 E7 g+ k7 V, p8 L1 \6 o
That means D is not sure the answer by seeing one white and one black. K: E4 l' E3 G3 O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.