d. Total variable costs? 1-6 Define the following terms: (a) cost behavior and (b) relevant range 1-7 What is meant by an activity base when dealing with variable costs? Give several examples of activity bases 1-8 Managers often assume a strictly linear relationship between cost and the level of activity. How can this practice be defended in light of the fact that many costs are curvilinear? Distinguish between discretionary fixed costs and committed 1-9 fixed costs. 1-10 Does the concept of the relevant range apply to fixed costs? Explain 1-11 What is the difference between a traditional format income statement and a contribution format income statement? What is the contribution margin? 1-12 1-13 Define the following terms: differential cost, sunk cost, and opportunity cost Only variable costs can be differential costs. Do you agree? 1-14 Explain