Which example best illustrates that gdp (gross domestic product) is not always a good indicator of economic health?

Firms like papa john’s, domino’s, and pizza hut sell pizza and other products that are differentiated in nature. while numerous pizza chains exist in most locations, the differentiated nature of these firms’ products permits them to charge prices above marginal cost. given these observations, is the pizza industry most likely a monopoly, perfectly competitive, monopolistically competitive, or an oligopoly industry?