Under variable costing, costs that are treated as period costs include: A. only fixed manufacturing costs. B. both variable and fixed manufacturing costs. C. all fixed costs. D. only fixed selling and administrative costs.

C. all fixed costs.

Explanation:

Under variable costing, all fixed cost are period cost. This make them non-capitalizable

Are treated as expenses and impact entirely on the net income

In other method some fixed cost are capitalzied through inventory but, in variable costing is not the case.

The only capitalized cost are the variable cost using this method.