Final answer:
The purpose of grandfather clauses and literacy tests in the late 1800s and early 1900s was to prevent Black people from voting in southern states.
Step-by-step explanation:
The purpose of grandfather clauses and literacy tests, used in southern states in the late 1800s and early 1900s, was to prevent Black people from voting. Grandfather clauses allowed illiterate white people to vote if their ancestors had been able to vote before the Fifteenth Amendment was ratified. Literacy tests were designed to disenfranchise racial or ethnic minorities, particularly African Americans, by requiring them to read a passage of text and answer questions about it.