Final answer:
African Americans gained the right to vote in 1870, followed by women in 1920, and Indigenous People gained US citizenship and the right to vote in 1924; hence the correct order is c) African Americans, Women, Indigenous People.
Step-by-step explanation:
When placing these groups in the order in which they legally gained the right to vote from earliest to most recent, we can refer to significant amendments and civil rights movements in American history. First, African American men gained the right to vote with the passage of the Fifteenth Amendment in 1870. Women of all races gained the right to vote with the Nineteenth Amendment, ratified in 1920. However, it was not until 1924, with the Indian Citizenship Act, that Indigenous People were granted U.S. citizenship and the accompanying right to vote, although various barriers continued to restrict this right for some time. Therefore, the correct order is c) African Americans, Women, Indigenous People.