Sources of external economies of scale include

A) larger plant size that allows the plant to take advantage of technology.
B) larger firm size that results in volume discounts.
C) larger industry size that `results in lower production costs.
D) All of the above are correct.

External Economies

Benefits that arise from a firm's actions but are enjoyed by other parties or firms without compensation, typically leading to an under-provision of a good or service.

Production Costs

Expenses incurred in the process of creating a product or service, including materials, labor, and overhead.

Industry Size

The scale or magnitude of economic activity within a specific sector, measured by criteria such as number of firms, total employment, or total revenue.