Which of the Following Statements Is True

Which of the following statements is true?

A) Native Americans have always been recognized as citizens of the United States.
B) Native Americans became U.S. citizens in 1868.
C) Native Americans became U.S. citizens in 1924.
D) Native Americans became U.S. citizens in 1965.
E) Native Americans have never become U.S. citizens in American constitutional law.