Nations with strong central governments were more successful in achieving stability than those with weaker governments. One of the main reasons for this is the fact that strong central governments are more effective in raising taxes.
Taxation serves several different purposes. The most obvious one is that taxes can be reinvested in social projects, such as buildings, schools, roads, healthcare, etc. Another advantage of taxes is that it makes the government accountable to the people. The people feel more entitled to demand satisfaction when they know the government is using their money. The government itself feels more pressured to fulfill its promises as well. Finally, taxation can increase national identity, because it gives people the feeling of working towards a common project, which contributes to the stability of the state (this is a serious problem in Africa, as state lines often cut across ethnic ones).
Democratisation in Africa had allowed investors to invest in business. The government was able to provide the needs of many impoverished areas as well as financial assistance was given to them by the World Bank.
I believe the answer is C, immunity because (immunity) means protection or exemption from somethings, especially an obligation or penalty. So the key word in the question is protection. I hope this helps and just stating I am NOT 100% sure.