To figure out why the Programmatic Guaranteed deal for a specialty foods business under-delivered in Display & Video 360 last week, the first step is to use the Deal Troubleshooter.

• See if the line item has multiple targeting assigned.
• Contact the publisher.
• Review the campaign-level targeting.
• Use the Deal Troubleshooter.

The correct answer is: Use the Deal Troubleshooter

Explanation: The Deal Troubleshooter is an intuitive, effective tool designed to diagnose issues with various deal types, including private auctions, guaranteed deals, non-guaranteed fixed deals, and open auction line items. It offers immediate insights into why a deal might not be performing as expected. This tool works with deals from any exchange integrated with Display & Video 360 and allows for targeted troubleshooting through filters for line items associated with multiple deals. It provides detailed explanations and quantifications for lost impression availability and identifies reasons a line item may not be capturing the available inventory, giving you a clear starting point to address and resolve the under-delivery issue.

Read more here: https://support.google.com/displayvideo/answer/6292894