Bill sells Mary a worthless coin that Bill incorrectly told Mary "belonged to an ancient Persian king and is of enormous value to coin collectors." Economists would call this an
◦ inefficient exchange because there were externalities involved.
◦ inefficient exchange since at least one party used false market information.
◦ efficient exchange, assuming Bill was not intentionally trying to trick Mary.
◦ efficient exchange since any type of voluntary exchange promotes efficiency.