Multiple Choice Question What does the long-run average-total-cost curve show? Multiple choice question. The lowest average total cost at which any chosen output level can be produced after the firm has had time to make adjustments in plant size The sum total of all of the short-run average-total-cost curves The lowest minimum short-run average-total-cost curve at which a firm must produce to make a profit The maximum level of output possible in the short run at all plant sizes