What would typically not be included in variable costs?

Variable costs are expenses that change in proportion to the production output. This means they increase or decrease based on the level of activity or production volume. Items such as raw materials, utilities, and direct labor associated with production can fluctuate as more or fewer products are made.

In that context, the fixed salaries of supervisory staff do not vary with production levels; they remain constant regardless of how much is produced. This differentiates them distinctly from variable costs, which are directly related to the volume of production or sales. Therefore, fixed salaries are categorized as fixed costs rather than variable costs.

The other options represent costs that typically fluctuate with production output. Raw materials and labor directly tied to production will increase when more units are produced, while utilities can also vary based on the level of manufacturing activity. Thus, the fixed salaries of supervisory staff stand out as not being included in variable costs.