Which Two Tests of a Resource's Competitive Power Determine Whether

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?

A) Whether the resource or capability is competitively valuable and/or is something that rivals lack.
B) Whether the resource or capability is rare and/or is hard to copy.
C) Whether the resource or capability is easy to copy.
D) Whether the resource or capability is competitively valuable and/or are there good substitutes available for the resource.
E) Whether the resource or capability is hard to copy and/or can be trumped by different types of resources and capabilities.