(A) Reference files contain assets that may match uploaded videos.
(B) Assets contain reference files that match against uploaded videos for claiming.
(C) Reference files comprise every instance of asset usage across YouTube.
(D) Content ID matches assets to the video reference files you upload.
The relationship of a reference to an asset is that Assets contain reference files that match against uploaded videos for claiming.
This question is a part of the Choose effective references lesson from the Music Assets unit. You can get answers to all the questions asked in this unit on our Music Assets Answers page.