Bill Sells Mary a Worthless Coin That Bill Deviously Told

Bill sells Mary a worthless coin that Bill deviously told Mary "belonged to an ancient Persian king and is of enormous value to coin collectors." Economists would call this an

A) efficient exchange, as any type of voluntary exchange promotes efficiency.
B) inefficient exchange, as at least one party used false market information.
C) efficient exchange, assuming Bill was not intentionally trying to trick Mary.
D) inefficient exchange because there were externalities involved.