In Africa how do the government solve the conflict of tribes moving freely across the continent name the tool and how that helps lesson conflict

NAIROBI, Kenya — From Sudan to South Africa, on shantytown streets and desert battlefields, tribal conflicts are fragmenting Africa’s nations and tormenting its peoples.
Even the anti-apartheid movement in South Africa often is beset by tribal rivalry that in recent months has seen black groups fighting each other, sometimes shattering black unity in the battle against the white government.

The answer i think is d

Cause of he different elevations  hope this ?