Which of the following groups is considered a static group?

A static group is defined by its consistent membership over time, meaning that the individuals in the group do not frequently change. In the context of the options provided, the performance population is typically comprised of individuals who remain unchanged for a particular analytical or reporting purpose, allowing for stable comparisons over time regarding performance metrics.

The other options represent groups that can change frequently. Non-furloughed employees can fluctuate as employees may come and go, and there may be variations based on employment status. Sales managers might also change due to various business dynamics, such as promotions, turnover, or restructuring. Classroom instructors can vary depending on class schedules, teaching assignments, or institutional changes. Therefore, performance population stands out as the group likely to have a stable and unchanging composition, making it the correct answer in this context.