With TrueView Video Discovery ads, advertisers can target:

  • A) The Google Display Network (GDN).
  • B) YouTube and the Google Display Network (GDN).
  • C) All of the listed answers are incorrect.
  • D) YouTube.

The correct answer is:

B) YouTube and the Google Display Network (GDN).

Explanation: While video content for TrueView ads must be hosted on YouTube, TrueView ads can appear on both YouTube and on video partner sites and apps in the Google Display Network for desktop computers and mobile devices.

Read more here: https://support.google.com/adwords/answer/2375464?hl=en