单项选择题

The passage supplies information for answering which of the following questions

(A) What do historiographers consider to be the precise difference between a nation and a nation-state
(B) What concepts in the field of historiography are considered unambiguous
(C) Are tribal areas without national spatial markers ever represented as nations
(D) What is an example of a nation represented in supra-national units
(E) How does the establishment of national spatial boundaries produce political problems