Answer:
Because of economies and diseconomies of scale.
Explanation:
Increasing returns to scale refers to the situation when a proportionate change in input leads to more than proportionate change in output. This may happen because of economies of scale. Â
Economies of scale are said to happen when the average cost of production decreases with the increase in the volume of output. Â
Decreasing returns to scale refers to the situation when a proportionate change in input leads to less than proportionate change in output. This may happen because of diseconomies of scale. Â
Diseconomies of scale occur when a firm experiences an increase in the average total cost as the volume of output increases.