A flat sign is your answer
The most important part of your personal interior decorating portfolio would be A. Before and after photographs. This would be a display of your actual skills in interior design.
Although your skills regarding choice in fabics, color chips and floor plans would also be an asset, before and after photographs would display your skills as a whole or shows the application of your different skills in the profession or at work.
Triadic would make the most sense for this picture : )
