Which of the following resulted from the travels of Zheng He and helped break down trade barriers?

The Forbidden City was built.

Japan was added to the Chinese territory.

Chinese merchants set up trading centers in Southeast Asia and India.

The Chinese allowed Portuguese merchants set up trading centers in China.

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: