8. For a manufacturing organization, which of the following is a period rather than a product cost?

a. Direct materials

b. Direct labor

c. Overhead

d. Wages of machine operators

e. Wages of salespeople

9. Total variable costs

a. vary in total, but not in proportion to a change in productive output or volume.

b. vary in total in an inverse relationship to productive output or volume.

c. vary in total in direct proportion to a change in productive output or volume.

d. do not vary within a defined range of activity or time period.

e. remain constant within a defined range of activity or time period.