In the first half of the 20th century, literacy tests, poll taxes, and grandfather clauses were passed by the southern states in order to

They were passed by the southern states in order to keep most African Americans from voting and violated the equal voting right that was guaranteed by the Fifteenth Amendment.

C)deny suffrage to African Americans.

Even after the Fifteenth Amendment guaranteed voting rights to all Americans regardless of their race, most southern states created obstacles to deny suffrage to African Americans, a process also known as "disenfranchisement" or "disfranchisement." Examples of such obstacles were literacy tests, poll taxes, and the grandfather clause, which all put up barriers meant to prevent black people from exercising their legal rights.

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: