• Download the Campaign Manager tag, append to the Display & Video 360 tag, and perform a SDF bulk upload
• Add the Display & Video 360 tags to Campaign Manager with the third party verification’s tracking link
• Add the integration code to the advertiser’s Basic Details and upload the tags to Display & Video 360
• In Display & Video 360, use the custom tag wrapper feature

The correct answer is: In Display & Video 360, use the custom tag wrapper feature

Explanation: To provide a safeguard against serving ads on the wrong sites, you can wrap your creatives with technology from third-party verification services, which can prevent your ads from accidentally serving in the wrong media. Display & Video 360 currently supports third-party verification for display creatives via Integral Ad Science, DoubleVerify, and Moat, although most other post-bid third-party verification services should work. Wrapping Campaign Manager-hosted creatives will prevent Display & Video 360 cost data from syncing over to Campaign Manager.

Read more here: https://support.google.com/displayvideo/answer/2995609