C knows the answer by deducing D is not yelling out the answer.
; p% M1 `$ j9 {: }& F+ h$ Itvb now,tvbnow,bttvbThat means D is not sure the answer by seeing one white and one black.
* c( K# q+ U. S. R3 J- HC saw B is wearing the white, hence he is wearing the black |