In design which principle is in effect when all elements in a design are in harmony and produce an undivided impact?

The principle in effect is known as "Unity." Unity in design ensures that all elements work together cohesively, creating a sense of wholeness and balance. This harmony enhances the overall impact of the design, making it visually appealing and effective in conveying its intended message. When unity is achieved, the viewer perceives the design as a single, integrated piece rather than a collection of disparate parts.