At the end of the Classical Age
(A) belief systems failed to survive the collapse of classical civilizations.
(B) only the Mediterranean Greco-Roman civilization experienced upheavals.
(C) the Huns (Hsiung-Nu) destroyed all great Eurasian classical civilizations.
(D) there was a religious upsurge as a result of social and economic problems.
(E) trade ceased to be important.
Answer: D