The correct answers are:
A. increased government militarization and the rise of rebel groups;
C. religious disputes between Muslim and non-Arab Sudanese;
The conflict in Sudan started in 2003 (again). The main reasons for that was that there were rebel groups on rise that were not pleased by the government's actions against the non-Arab population in Darfur. The government was very strict and was segregating the non-Arab population for quite some time, so the tensions needed very little to escalate. The government than ordered the military to destroy the rebel groups and to perform an ethnic cleansing of the non-Arab population. That resulted in hundreds of thousands of deaths of innocent people.