The account that shows the sources of and claims on assets is called Select one: O a. Owner's equity O b. Fixed cost O c. Assets O d. Liabilities Mixed costs change in total but not proportionately with the change in activity level. Select one: True O False Which of the following is true about variable costs? Select one: a. Variable costs are constant in total across changes in activity O b. None of the above O c. Variable costs vary in total across changes in activity O d. Variable costs vary on a per unit basis