Use the following list, which gives some information about seven firms.
- Coca-Cola cuts its price below that of Pepsi in an attempt to increase its market share.
- A single firm, protected by a barrier to entry, produces a personal service that has no close substitutes.
- A barrier to entry exists, but the good has some close substitutes.
- A firm offers discounts to students and seniors.
- A firm can sell any quantity it chooses at the going price.
- The government issues Nike an exclusive licence to produce golf balls.
- A firm experiences economies of scale even when it produces the quantity that meets the entire market demand.
In which of the seven cases might monopoly arise?