The four determinants in Porter's model of international competitive advantage include the following, EXCEPT: political and economic institutions. The correct determinants are related and supporting industries, factors of production, and demand conditions.

The four main determinants of national competitive advantage according to Michael Porter's Diamond Model are (1) factor conditions, (2) demand conditions, (3) related and supporting industries, and (4) firm strategy, structure, and rivalry. Political and economic institutions are not one of the core determinants in Porter's original model; however, they can be considered as part of the two additional variables that were later included to complement the model: (5) chance and (6) government, which could be related to political and economic institutions.

1. Factor conditions refer to a nation's position in factors of production, such as skilled labor and infrastructure, necessary for competing in a given industry. 2. Demand conditions indicate the nature of home-market demand for the industry's product or service. 3. Related and supporting industries suggest the presence or absence in the nation of supplier industries and related industries that are internationally competitive. 4. Firm strategy, structure, and rivalry refer to the conditions in the nation governing how companies are created, organized, and managed, as well as the nature of domestic rivalry.

These determinants interact with each other to create the conditions where firms can develop competitive advantage in particular industries.

Extra: Porter's Diamond Model suggests that the national home base of an organization plays a crucial role in shaping the extent to which the organization can build a competitive advantage in the global market. The model proposes that for an industry to be globally competitive, all four determinants should favorably interact. The 'chance' and 'government' can also influence each of the four determinants but are considered as external factors that can shake up or enhance the diamond's effectiveness. For example, government policy can influence the direction of factor development or increase the rivalry among firms. Most importantly, Porter emphasizes that firms must actively engage in creating, reinforcing, and sustaining the factors that lead to competitive advantage. His model has been very influential in the fields of economics, business strategy, and international trade as it shifts focus not just on the company but also on the surrounding environment and conditions necessary for success.