Ha, that was a lesson!:)
I did not have a clue before this task from Amy Simmons that there is something like a "treatment" proposal in the photographic industry, and that there are some common standards of how the treatment document should look like.
I supposed to create the mood boards with references based on my own photos or/and external sources, to explain my approach to task requirements articulated in a brief.
Treatment is an important part of the pre-production process. It is a form of the proposal but its more image-based than the normal proposal. There are references organised in a mood boards to explain the approach.
Some useful information about the treatment.