How did improvements in printing affect the Tang and Sung dynasties? Choose two correct answers. gave more people access to literature
made China less vulnerable to invasion
allowed use of paper currency for trade
led to stronger ties with Korea and Japan
encouraged dependence on foreign trade

it gave more access to literature and allowed use of paper for currency in trade

Explanation:

got it right on edge test

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation: