Which of the following best illustrates change over time in mongolia:

a.) the mongol tribes fought each other for centuries, until genghis khan united them, he set off to conquer the world, and expanded the empire, today, mongolia is a small country, but they still revere genghis khan as a national hero.

b.) the mongol tribes were united but began fighting when genghis came to power, while he expanded the empire, today, the people of mongolia see him as a villain.

c.) the mongolian empire was huge, but the tribes began to fight among themselves and eventually they lost their power over areas they had conquered. today, mongolia is a small country that consists of many tribes that still have the animosity towards one another.