Electromagnets are often used for sorting metals in recycling centers. What makes electromagnets useful for this purpose? OA. They attract items containing iron when the electricity is off and drop the items when the electricity is turned on. OB. They attract all mostly metal items when electric current flows and drop the items when the current is turned off. OC. They attract items containing iron when electric current flows and drop the items when the current is turned off. OD. They attract all mostly metal items when the electricity is off a drop the items when the electricity is turned on.​