The correct answer is C.
Cajuns are an ethnic group that live in the US, in the Southern state of Louisiana. They are mostly descendants of the Acadian exiles (who in turn were the descendants of the French colonists).
Cajun and black cowboys worked for the cattle industry in th 1860s and 1880s. In the case of the Cajuns in Louisiana, they were in charge of the mainland transportation of the cattle until they reached the ports where it was placed in boats to be shipped somewhere else.