When red copper wire is heated on a Bunsen burner flame, the surface of the copper turns black. The wrong statement below is

A. The surface of the red copper wire turns black because copper oxide
is formed.
B. The surface of the red copper wire turns black because copper is
reduced.
C. When the copper wire that has turned black is placed in dilute
sulphuric acid, blue colour can be seen in the solution
D. Mass is increased after the copper wire has turned black​