Answer:
A. They do not want one ruler to have all the power over people.
Explanation:
As stated above, "most countries" as of today follow the "rule by law." This is done in order to prevent the leader from abusing his powers and to have the sole control over the people. To do this, he has to follow the Constitution, which states the basic laws that all people should follow. This ensures that justice will prevail in the nation.
People take active part in electing their leaders, thus, they have to be smart in choosing them to prevent being ruled by an incompetent ruler.