You want to manage frequency within your Programmatic Guaranteed deals across multiple publishers. At what level in your Display & Video 360 account settings should you set this up?

Why this is correct:

Display & Video 360 can look across all of the underlying insertion orders and line items simultaneously. If a user hits the established frequency cap on one publisher’s site, DV360 will intelligently “pass” on subsequent bid requests for that same user when they visit a different publisher’s site within the same campaign. This allows the system to minimize ad overexposure and reinvest those saved impressions into reaching brand-new, unique users.

We don’t have option to set FC on Advertiser level so we can ruled out that option.