What is the difference between variable costs and fixed costs? Select one: a. Total fixed costs remain the same. Total variable costs remain the same. b. Fixed costs per unit remain the same. Variable costs per unit remain the same. c. Total fixed costs per unit remain the same. Fixed costs per unit remain the same. d. Total variable costs per unit remain the same. Variable costs per unit remain the same. e. Total fixed costs remain the same. Variable costs per unit remain the same.