Answer:
Price leadership
Step-by-step explanation:
This is an example of price leadership. In this example, we learn that the drinks compete in the market, but Optimax enjoys the largest market share. Moreover, we also learn that whenever Optimax changes its price, the other ones follow. This occurs because the dominant firm (price leader) sets the price of the goods in the market. As this firm dominates most sales of the drink, the other firms have no option but to match the prices in order to try to hold on to their market share.