Answer:
d
Step-by-step explanation:
An Oligopoly is when there are few large firms operating in an industry. While, a monopoly is when there is only one firm operating in an industry.
Oligopolies are characterised by:
price setting firms
product differentiation
profit maximisation
high barriers to entry or exit of firms . There is a high cost of entry into the airline industry due to the high cost of the business
downward sloping demand curve