In the 1990s, as military leadership changed in west and central africa,
the economy became much healthier
democracy gradually developed
rebel groups incited violence
the public demanded a dictatorship

Hello there.

In the 1990s, as military leadership changed in west and central africa, .

the public demanded a dictatorship

The economy became much healthier (This isn't your answer)

Democracy gradually developed (This isn't your answer either)

Rebel groups incited violence (not your answer because it is false)

The public demanded a dictatorship (this is most likely going to be your answer because the the rest of them are false statements) 

So, try going with option D. as the answer in the blank

Good Luck! 

Increasing the release of greenhouse gases and pollution