Which of these reasons was NOT a reason for the decline of Rome?

Can you post a picture with the options or reply with the options ? (:

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