C knows the answer by deducing D is not yelling out the answer.www3.tvboxnow.com& @6 R) z3 q+ S: x3 o
That means D is not sure the answer by seeing one white and one black.$ l' [3 ]. Y9 j& B6 H
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.