What is one reason why democracies in sub-Saharan Africa tend to be fragile?

a. People in sub-Saharan Africa do not have any democratic institutions.
b. The population in many countries is too low to support national elections.
c. Ethnic conflicts, made worse by poorly drawn borders, destabilize many attempts at government.
d. People in sub-Saharan Africa believe that democratic institutions are being pushed on them by the West.