Answer: d. economies of scale
Explanation:
Trash Collection can be a costly business because it includes going around the city, paying workers, high vehicle input costs and the like. These costs would need to be recovered and have less chances of doing so if the firms had to compete amongst themselves for customers.
A monopoly-promoting license giving a firm significant control would lead to Economies of scale that would ensure that they had enough customers for their costs to reduce as they offer services to the people as their costs would then reduce as they service more people without having to worry about competition.
