Final answer:
Exclusive publisher partnerships can be established through Preferred Deals, Private Auctions, and Programmatic Direct, with each offering varying levels of exclusivity and control.
Step-by-step explanation:
The inventory sources that allow for exclusive publisher partnerships are Preferred Deals, Private Auctions, and Programmatic Direct. Open Auction Only does not typically allow for exclusive partnerships because it is accessible to any advertiser on an exchange. Preferred Deals are where a publisher offers inventory to a single advertiser before making it available to others. Private Auctions are invite-only auctions where a publisher invites a select group of advertisers to bid on inventory. Lastly, Programmatic Direct is where a publisher sells inventory directly to an advertiser at a fixed price, offering the most control and exclusivity.