C knows the answer by deducing D is not yelling out the answer. 4 O' T) A2 x6 q2 zos.tvboxnow.comThat means D is not sure the answer by seeing one white and one black.os.tvboxnow.com) W2 B4 A! K" p0 V* m( `9 B+ v' z7 F
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.