Oligopolistic industries are characterized by a few dominant firms and substantial barriers to entry. This means that there are only a few large firms that dominate the industry, and it is difficult for new firms to enter and compete in the market.

Here is a detailed explanation of why option 'A' is the correct answer:

Dominance of a few firms:
- In an oligopolistic industry, there are only a few large firms that control a significant portion of the market share. These firms have a strong influence on the market dynamics and competition.
- The dominance of these few firms allows them to have a significant impact on pricing strategies, product differentiation, and overall market conditions.
- The actions of one firm in the industry can have a direct impact on the others, leading to strategic interdependence.

Substantial barriers to entry:
- Oligopolistic industries often have substantial barriers to entry, which make it difficult for new firms to enter and compete in the market.
- These barriers can include high startup costs, economies of scale enjoyed by existing firms, strong brand loyalty towards existing firms' products, and legal or regulatory barriers.
- Existing firms in the industry may also engage in strategic actions to deter new entrants, such as aggressive pricing or product innovation.

Impact on competition and market behavior:
- The dominance of a few firms and the barriers to entry create a unique market structure where competition is limited and firms must carefully strategize to maintain their market position.
- Due to the interdependence among the few firms, their pricing decisions and strategic moves can have a significant impact on the market as a whole.
- Firms in oligopolistic industries often engage in non-price competition, such as advertising, product differentiation, and innovation, to gain a competitive edge.

Conclusion:
In summary, oligopolistic industries are characterized by a few dominant firms and substantial barriers to entry. This market structure creates a unique competitive environment where the actions of a few firms have a significant impact on the market dynamics. Understanding these characteristics is crucial for analyzing and predicting the behavior of firms in oligopolistic industries.