What Is the Long-Run Average Cost Curve

What is the long-run average cost curve?

A) A graphical representation of the total variable cost.
B) A measurement of the percentage of an industry's total sales which is controlled by the four largest firms.
C) A graphical representation of those costs that do not vary with the level of output.
D) A graphical representation of the average costs of production in the long run.
E) A portion of the short-run average total cost curve.