C knows the answer by deducing D is not yelling out the answer. , l9 V8 y- C4 M5 i* J1 U0 Htvb now,tvbnow,bttvbThat means D is not sure the answer by seeing one white and one black.( k3 \3 r' P! c# p0 j
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.