Which of the following costs/expenses is included in product costs under both absorption costing and variable costing?

A. Office equipment depreciation.

B. Variable manufacturing costs.

C. Supervisory salaries.

D. Variable selling expenses.

What will result from an increase in the activity level within the relevant range?

A. A proportionate increase in total fixed costs.

B. An unchanged fixed cost per unit.

C. A decrease in fixed cost per unit.

D. An increase in fixed cost per unit.