C knows the answer by deducing D is not yelling out the answer. 5 ?7 x' O7 {) p- d: sThat means D is not sure the answer by seeing one white and one black. % ^" u; Q& s: ]: t: BTVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。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.