What are the answer choices?
Cultural: The Enlightenment philosophy desacralized the authority of the monarchy and the Catholic Church, and promoted a new society based on reason instead of traditions.
Social: The emergence of an influential bourgeoisie which was formally part of the Third Estate (commoners) but had evolved into a caste with its own agenda and aspired to political equality with the clergy (First Estate) and the aristocracy (Second Estate).
Financial: France's debt, aggravated by French involvement in the American Revolution, led Louis XVI to implement new taxations and to reduce privileges.
Political: Louis XVI faced strong opposition from provincial parlements which were the spearheads of the privileged classes' resistance to royal reforms.
Economic: The deregulation of the grain market, advocated by liberal economists, resulted in an increase in bread prices. In periods of bad harvests, it would lead to food scarcity which would prompt the masses to revolt.
Constantine reigned during the 4th century CE and is known for attempting to Christianize the Roman Empire. He made the persecution of Christians illegal by signing the Edict of Milan in 313 and helped spread the religion by bankrolling church-building projects, commissioning new copies of the Bible, and summoning councils of theologians to hammer out the religion's doctrinal kinks. Constantine was also responsible for a series of important secular reforms that ranged from reorganizing the Roman Empire's currency system to restructuring Rome's armed forces. His crowning achievement was his dedication of Constantinople as his new imperial capital in 330.
The answer is the North Vietnamese took over the South Vietnam spreading communism Southward and this proved the domino theory (if one country come under the influence of communism, the surrounding countries would follow).