Why did many states and empires gain more power over people and territories over the course of medieval and early modern times?

The correct answer to this open question is the following.

Many states and empires gained more power over people and territories over the course of medieval and early modern times through war and conquering weaker provinces or territories.

The Medieval years of the Middle Ages was a time in human history where powerful monarchies in Europe and other regions exerted total power and control over their subjects, who had no rights. They just had to serve their king. In their ambition to extend their power over other lands, the King or Emperor's armies went and waged war to other nations and conquered to exploit their people and raw materials.

It also was a time of exploration and navigation to discover new navigational routes to other far lands to do exactly the same.

i believe your answer is d)