C knows the answer by deducing D is not yelling out the answer.3 @" ?$ A n% }; z0 r5 X' }2 _
That means D is not sure the answer by seeing one white and one black. * \: b; X* B( }, s* Ywww3.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.