Why was the fifteenth amendment unable to protect african americans' voting rights?
a. the fifteenth amendment applied to only some districts.
b. states were still able to impose voting restrictions based on literacy or property qualifications.
c. some states refused to recognize constitutional amendments.
d. the fifteenth amendment dealt with citizenship, not voting rights.

D. The Fifteenth Amendment dealt with citizenship, not voting rights.

Explanation:

The Court wrote: The Fifteenth Amendment does not confer the right of suffrage upon anyone. It prevents the States, or the United States, however, from giving preference, in this particular, to one citizen of the United States over another on account of race, color, or previous condition of servitude.

b. second continental congress