C knows the answer by deducing D is not yelling out the answer. 7 d( R: ]' k4 z; \1 j/ e, O4 e! @TVBNOW 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。That means D is not sure the answer by seeing one white and one black. 0 [5 G' G0 j' m% E$ a7 a" TTVBNOW 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.