Homer Has Been Asked to Create a Monthly Advertising Message

Homer has been asked to create a monthly advertising message and send it by bulk e-mail to all e-mail addresses collected from customers who have purchased products from the company. What should Homer include in the bulk e-mail message to ensure customer privacy?

A) The customer's e-mail address in the body of the message
B) A section in which recipients can provide feedback about the company
C) An opt-out option for recipients to stop receiving future advertising messages from the company
D) An opt-in option to receive additional similar messages from related companies