Rhythm: A continual flow or sense of movement created by a pattern or repetition of visual units. ... Harmony: The quality of how the visual elements are working together in a composition. It is achieved when all elements have unity and cohesion, giving a sense of completion to an artwork.Harmony. Harmony in art and design is the visually satisfying effect of combining similar, related elements. For instance: adjacent colors on the color wheel, similar shapes etc. Harmony.
So there for C. Similarities would be ur answer
hope this helps
You would want to mix he dark one first so that you can slowly put lighter color I'm so you know how much to put in
