Which of the following examples best illustrates the spirit of "permission marketing"?
A direct mail sales promotion includes a phone number for customer service next to the statement, "to remove this address from future mailings, please call."
A receipt given to a shopping mall's customers includes a sentence at the bottom about an upcoming design show that says "go to this website to receive more mall news and invitations."
The monthly email newsletter sent by an investment firm to its clients includes a link at the bottom labeled "Unsubscribe."
A retailer offering $5 to customers at the cash register if they agree to be added to a mailing list.