Which concept involves placing design elements in a sequence?

The concept of hierarchy involves arranging design elements in a sequence to signify importance or to create a structured flow of information. In architectural and design contexts, hierarchy helps to guide the viewer's eye by establishing a clear order among the elements. This can be achieved through variations in size, color, placement, or visual weight, enabling certain features to stand out as more significant while others recede into the background. Such an arrangement assists users in navigating a space or understanding information more intuitively by prioritizing elements according to their intended impact.

In contrast, scale refers to the size of an object in relation to something else, and while it can inform hierarchy, it doesn't inherently involve sequential placement. Contrast involves differences in attributes such as color or texture to create visual interest or emphasis, but it does not directly address the organization of elements in a sequence. Color pertains to the hue and tone used in design, which can support hierarchical design but does not define the concept itself. Thus, hierarchy is the most appropriate choice when discussing the sequential arrangement of design elements.