Why was it necessary in 1868 to apply the federal Bill of Rights to the states with the 14th Amendment?

Question

to establish civil rights for visible minorities
to establish civil rights for visible minorities

to prevent states from continuing the practice of slavery
to prevent states from continuing the practice of slavery

to give the federal government the power to prevent rebellions
to give the federal government the power to prevent rebellions

to establish proper checks and balances between state and federal governments

Answer 1

to establish proper checks and balances between state and federal governments