Final answer:
In presentation design, variants are alternate designs within a theme including different colors, fonts, effects, and slide elements.
Step-by-step explanation:
In the context of presentation design, such as in PowerPoint or similar software, the alternate designs that can include different colors, fonts, effects, and slide elements within each theme are called variants. These variants allow the presenter to maintain a consistent look and feel throughout the presentation while providing some variation and visual interest from slide to slide. For example, if the main theme is professional and sleek, variants may offer different color schemes or background graphics that align with this aesthetic but give choices for individual slides to stand out.