C knows the answer by deducing D is not yelling out the answer. ) T" S1 ?7 u; W2 h+ k) b+ u a! v' GThat means D is not sure the answer by seeing one white and one black.公仔箱論壇4 g% v! m6 x2 A6 @+ J" T4 S$ e
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.