parts a,b,c please, thank you!!

7. A cost which remains constant per unit at various levels of activity is a A) variable cost. B) fixed cost. C) mixed cost. D) manufacturing cost. 8. A fixed cost is a cost which A) varies in total with changes in the level of activity. B) remains constant per unit with changes in the level of activity. C) varies inversely in total with changes in the level of activity. D) remains constant in total with changes in the level of activity. 9. Miley, Inc. has excess capacity. Under what situations should the company accept a special order for less than the current selling price? A) Never B) When additional fixed costs must be incurred to accommodate the order c) When the company thinks it can use the cheaper materials without the customer's knowledge D) When incremental revenues exceed incremental costs