A monopoly is a market structure where there is only one supplier of a product and many buyers. An example of a monopoly is Microsoft; it is a price setter in the market. Abuse of monopoly power can occur when a firm dominates the market meaning no competitors within the industry. This abuse could be in form of limiting output or setting higher prices to benefit from supernormal profits . This therefore leads to less choice for consumers.Over time, monopolies can become less innovative because they do not have competition and causing the market to fail and be inefficient; the price mechanism fails to take into account all of the costs and/or benefits of providing and consuming a good.
If supply decreases and demand remains stable, the price mechanically moves up since richer people are ready to pay more to get gasoline. Of course companies selling gasoline want to maximize their profit so they will increase the price. Right answer is A.