问题如下：
A company is experiencing economies of scale when:
选项：
A.cost per unit increases as output increases.
B.it is operating at a point on the LRAC curve where the slope is negative.
C.It is operating beyond the minimum point on the long-run average total cost curve.
解释：
B is correct.
Economies of scale occur if, as the firm increases output, cost per unit of production falls. Graphically, this definition translates into a long-run average cost curve (LRAC) with a negative slope.
考点：规模经济
解析：经济规模阶段，产量的增加会导致单位成本的降低。A不入选
在长期总成本曲线上，这表示为曲线下降的阶段，即曲线的斜率为负。B入选
该阶段位于曲线最低点的左侧而非右侧。C不入选
latc 和 lrac 的区别是什么
