An advertiser is charged for a TrueView in-display ad when a viewer:

Q)  An advertiser is charged for a TrueView in-display ad when a viewer:
  A)  watches the entire ad.
  B)  watches a TrueView in-stream ad after watching an in-display ad.
  C)  chooses to watch the ad by clicking a thumbnail.
  D)  shares the ad.