Shelly was creating a slide for her presentation. she made sure that the elements used in that slide would complement each other. which principle of design has shelly used in her presentation? shelly used the *blank* principle of design in her screen.

Explanation:

Principles of Design are the basic idea that help one to create or produce good visual designs. They are actually fundamental strategies that intend to practice better designs visually.

Harmony is such a principle of design that collects all the parts of visual image together. Each element present in the design complements each other  due to harmony. So this can be achieved by repeating and establishing rhythm.

So Shelly should use Harmony in her design.

I hope it will help you!