Question 5 Homework. Unanswered Which of the following is true of fixed and variable costs? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Variable costs per unit increase as you produce and sell more units. b Fixed costs per unit decrease as you produce and sell more units. The contribution margin per unit increases as you produce and sell more units. d Total fixed costs increase as you produce and sell more units