Which of the following is an example of a labor resource?

It developed as a reaction to the impact of european colonialism in africa on peoples of african descent. in the  mid-20th century, activists in africa adopted pan-africanism as a rallying cry for independence from colonial rule. some african pan-africanists sought to unite the continent as one independenthope it was useful

Southern secession is the event or issue that historians can gain insight from this excerpt.