Answer:
Monopoly.
Step-by-step explanation:
A monopoly is a market structure which is typically characterized by a single-seller who sells a unique product in the market by dominance. Thus, it is a market structure wherein the seller has no competitor because he is solely responsible for the sale of unique products without close substitutes. Any individual that deals with the sales of unique products in a monopolistic market is generally referred to as a monopolist.
For example, a public power company that serves as the only power utility provider to the general public.
Hence, if a single firm provides the entire market supply. Then type of market structure does this firm likely operate in is monopoly.