Answer: Option (b) is correct.
Explanation:
Economics of scale occurs when a firm's long run average total costs decreases as there are more number of units produced.
Basically, economics of scale is a cost advantage that is experienced by the firms or companies by increasing the level of production.
This is happened because of the indirect relationship between the per unit fixed cost and output level. The larger the output produced results in lower per unit fixed cost.
There are two types of economies of scale that are internal and external economies of scale.