Final answer:
Due to resource immobility in the resource-based model, resource differences between firms tend to last a long time option (c), contributing to sustained competitive advantages for firms that capitalize on their unique resource bundles and core competencies.
Step-by-step explanation:
Due to resource immobility, a critical assumption in the resource-based model of a firm, the correct answer is C) Resource differences between firms last for a long time. Resource immobility refers to the notion that resources are not easily transferable or replicable across firms and this difficulty in moving or copying resources leads to sustainable competitive advantages.
Firms leveraging their unique resource bundles, which may comprise of specialized knowledge, proprietary technology, or brand reputation among others, can maintain a competitive edge that is not readily duplicable by competitors.
Furthermore, the resource-based view outlines that firms should focus on their core competencies, or their unique strengths and resources, that competitors cannot easily imitate. This also ties into the theory of comparative advantage in business and international trade, which suggests that companies should specialize in areas where they have a unique advantage, leading to greater productivity and success.
These concepts emphasize the importance of focusing on and developing unique capabilities as a pathway to more sustained competitive advantages in the marketplace.