For what reason do most sellers require customers to have their receipts in order to exchange or return purchased items?

For what reason do most sellers require customers to have their receipts in order to exchange or return purchased items?

	The receipt contains coded information that the seller needs to prepare and analyze the trial balance.
→	Sellers wish to ensure that the sale in question was rung up on the register in the first place.
	This is a legal requirement mandated by a federal law.
	The receipt is serving as a promissory note.
	To create an environment in which customers do not want to return items.