Use the graph to answer the question. A typical long run average total cost curve is drawn. Cost is on the vertical axis and output on the horizontal axis. There are four points. Point A is at coordinates 0, 6. Point B is at coordinates 3, 3. Point C is at coordinates 7, 3. Point D is at coordinates 10, 6. These points are connected by a smooth line. Between points B and C, the long-run average total cost curve is characterized by ________ because the firm is experiencing ________ returns to scale. constant returns; constant economies of scale; constant economies of scale; decreasing diseconomies of scale; constant diseconomies of scale; decreasing