Answer:
a. African American cavalry and soldiers who served in the frontier wars.
Explanation:
The Buffalo Soldiers were "African American cavalry and soldiers who served in the frontier wars."
The Buffalo Soldiers were formed in 1866 at Fort Leavenworth, Kansas. Their purpose is to apprehend bandits from Texas to the Dakotas and fight Indians during the American civil war.
They were also utilized in the support of the country's westward expansion. Their role includes protection and safeguarding of U.s mails.
Hence, in this case, the correct answer is option A "African American cavalry and soldiers who served in the frontier wars."