For launching Display & Video 360 deal negotiations for exchanges integrated with deal sync, the responsibility falls on the advertisers.

• The publishers are responsible.
• The Display & Video 360 representatives are responsible.
• The publishers and advertisers are both responsible.
• The advertisers are responsible.

The correct answer is: The advertisers are responsible

Explanation: Within Display & Video 360, deal negotiations for exchanges integrated through the Seller API are primarily the responsibility of advertisers. This integration allows for the automatic synchronization of deal details, creating a streamlined inventory source. Whether initiated by sellers through the Deal Sync API or by advertisers, both parties have the capability to propose, amend, and accept deal terms directly within Display & Video 360. Specifically, when advertisers initiate the process, it often begins with a Request for Proposal (RFP), detailing essential campaign specifics like budget and scheduling. This facilitates a collaborative and efficient negotiation process, allowing advertisers to actively manage and launch their deals.

Chapter 12: Programmatic Guaranteed Deals in Display & Video 360

Read more here: https://support.google.com/displayvideo/answer/7505945