Yes aids had done more harm than good. The reason why because people in Africa didn't have aids and when aids started to spread around the whole world the Africa gotten so sick they started to die.
The principle of uniformitarianism states that geologic processes that we observe today occurred in the same way in the past. The correct option among all the options that are given in the question is the last option. Incidents such as floods, hurricanes and huge storms have not occurred only in the present time, but it has been occurring in the past as well.
Africa's currency is called Rand. Hope that helps! :)