C knows the answer by deducing D is not yelling out the answer.
% s, M$ f/ y6 _1 [9 Stvb now,tvbnow,bttvbThat means D is not sure the answer by seeing one white and one black.tvb now,tvbnow,bttvb& U- T! u* q0 V! u) m5 j5 D
C saw B is wearing the white, hence he is wearing the black |