【单选题】

The passage supplies information for answering which of the following questions
A．(A) What do historiographers consider to be the precise difference between a nation and a nation-state

B．(B) What concepts in the field of historiography are considered unambiguous
C．(C) Are tribal areas without national spatial markers ever represented as nations
D．(D) What is an example of a nation represented in supra-national units
E．(E) How does the establishment of national spatial boundaries produce political problems