The term ‘‘variable costs’’ refers to a_ All costs which are likely to respond to the amount of attention devoted to them by a specified manager b All costs which are associated with marketing, shipping, warehousing, and billing activities c All costs which do not change in total for a given period of time and relevant range but become progressively smaller on a per unit basis as volume increases All manufacturing costs incurred to produce units of output All costs which fluctuate in total in response to small changes in the rate of utilization of capacity.

(CMA adapted.)