Answer:
Option (c) is correct.
Option (d) is correct.
Explanation:
1. Under the market structure of natural monopoly, its cost of production states that initially there is a need of large amount of investment and after that the marginal cost of producing output becoming so low that the average total cost keeps on falling until the point at which whole market being served.
2. Municipal Power Light, the local supplier of electricity is an example of natural monopoly. In this type service, there is a need of large amount of investment in setting the cables infrastructure and grid and after that the marginal cost of providing each additional unit of electricity is so low that the average total cost keeps on falling which is represented by the downward sloping average total cost curve.