Answer: Economies of scale
Step-by-step explanation:
Economies of scale is the saving in costs that is gained by an increase in the level of production. Economies of scale exist when there is an expansion in a firm's production thereby leading to a decrease in the firm's long-run average costs.
A reason for economies of scale is due to specialization of labor and machinery. An increase in sales of bikes from 1200 to 2400 with a lower long run average cost shows that there's economies of scale.