How Were South African Politics Decisively Transformed in and After

How were South African politics decisively transformed in and after 1990?

A) by the brutal spillover of civil wars in neighboring Angola and Zaire
B) by the dramatic example of Rhodesia's transition to minority rule as Zimbabwe
C) by the return to the politics of apartheid that had been eliminated in the 1960s
D) by the cumulative economic effects of sanctions imposed on South Africa by the United States and the Commonwealth during the 1980s
E) by the release of political prisoner Nelson Mandela and the legalization of the African National Congress