Economies of scale are indicated by:

A) the rising segment of the average variable cost curve.
B) the declining segment of the long-run average total cost curve.
C) the difference between total revenue and total cost.
D) a rising marginal cost curve.

Economies of scale refer to the cost advantages a company gains as it increases production levels. The declining segment of the long-run average total cost (LRATC) curve shows that as a company increases production, its average cost per unit decreases. This indicates economies of scale, as the company is able to spread its fixed costs over a larger output, leading to lower unit costs. The rising segment of the average variable cost (AVC) curve, on the other hand, indicates diseconomies of scale, as the company is experiencing increasing variable costs for each additional unit produced. The difference between total revenue and total cost (profit) is not necessarily indicative of economies of scale, as it depends on the level of output and costs involved. A rising marginal cost (MC) curve also indicates diseconomies of scale, as it shows that the cost of producing each additional unit is increasing.