If a cost's step-cost behavior follows very narrow steps, the costs may be approximated using:

(A) fixed costs assumptions.
(B) step-fixed cost assumptions.
(C) straight variable cost assumptions.
(D) mixed cost assumptions.

The correct answer is (C) straight variable cost assumptions.

Explanation:

If the total cost increases with small increases in activity, it may be referred to as a step-variable cost.

you have to put the parentheses like this:

in fact, you have to perform the operation inside parentheses first, and then proceed in order:

answer; realistic job preview;