A design option is one possible solution for a particular design issue. Each design option set contains one primary option and one or more secondary options. When you create a set, Revit LT also creates a primary option, which you must edit to add its elements. (See Editing a Design Option.) Use the following procedure to add secondary design options.
To add a design option
Design Options panel
The default option name displays under the option set.

The Make Primary button promotes a secondary option to the primary option. The former primary option becomes a secondary option.
In the current view, elements in the main model display in halftone to distinguish them from the design option that you are editing. For further instructions, see Editing a Design Option.
If the design option that you just created is a primary option, by default it displays in all project views that are not dedicated to other design options. If the option is secondary, it does not appear in any project views by default. See Viewing Design Options.