C knows the answer by deducing D is not yelling out the answer. # m6 ~( x. G* x; l7 S& I% K) K公仔箱論壇That means D is not sure the answer by seeing one white and one black.+ }% g$ W3 O6 @2 v" Y9 }
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.