Answer:
D. are conceptual . . . are concrete
Step-by-step explanation:
It can be used interchangeably or be synonymous with country and state. A nation, therefore, is described as a community of people united by culture, beliefs and customs; while state refers to a certain territory in which it has jurisdiction. Thus country becomes theoretical, or the concept, when state is concretely expressing the theory.
Hopefully, this helps! :D