Which two tests of a resource's competitive power determine whether a company's competitive advantage can be sustained in the face of active competition?

Whether the resource or capability is rare and$/$or is hard to copy

Whether the resource or capability is competitively valuable and$/$or there are good substitutes available for the resource

Whether the resource or capability is competitively valuable and$/$or is something that rivals lack

Whether the resource or capability is hard to copy and$/$or can be trumped by different types of resources and capabilities