Which summary of the 19th century most clearly emphasizes the theme of economic change?

The answer is the economy changed from a rural, agricultural one to an urban one that included industrial production. The explanation behind this is because it was completed without power, when the Cainites got hold of the banks, Wall Street, they organized the money, and they could then govern anything that comprises Social Engineering which is the promoter for social change.

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: