Which of the following statements concerning the long - run average cost​ (LRAC) curve is correct​?A.The LRAC curve is derived from a series of short-run marginal cost curves.B.The LRAC curve represents the least-cost input combination of inputs for producing each level of output.C.As output​ increases, the amount of capital employed by the firm is held constant along the LRAC curve.D.The short-run cost curve at the minimum point of the LRAC curve represents the least-cost plant size for all levels of output.