C knows the answer by deducing D is not yelling out the answer. ) N* B' J9 p& A* G& F) j2 i; oThat means D is not sure the answer by seeing one white and one black. 1 B% I6 _1 w/ k6 w$ k5.39.217.76C 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.