Why are africa’s savannah’s the most populated areas in the country

This is due to the high richness of its ecosystem. The savannah is considered the fourth largest biome in the world in area, with about 15 million km2, which corresponds to about 33% of Earth's continental surface, and is home to 20% of the world's population.

i think it would be reparing roads  

which statement explains one of the reasons world war 1 was so much more destructive than earlier conflicts