The true beginning of the modern state system marked the end of

Correct option is B

The true beginning of the modern state system is widely recognized to have been marked by the end of the Thirty Years' War, through the Peace of Westphalia in 1648. This pivotal event in European history concluded with the signing of two peace treaties of Osnabrück and Münster, collectively known as the Peace of Westphalia. These treaties are considered foundational in the development of the sovereign state system we recognize today. The Peace of Westphalia is credited with establishing the concept of sovereign states governed by a recognized set of international laws and norms. It effectively ended the medieval practice of overlapping authorities and allegiances and laid the groundwork for the principle of national self-determination.