Video ads can run on:

A) YouTube only
B) YouTube and the Display Network
C) The Display Network and video partner sites and apps
D) YouTube and video partner sites and apps

The correct answer is:

D) YouTube and video partner sites and apps

Explanation: Video ads can appear on YouTube and on video partner sites and apps across the Display Network.

Read more here: https://support.google.com/partners/answer/2375464