Final answer:
The growing Protestant sect whose aspirations contributed to the outbreak of the Thirty Years' War was Calvinism (B). The spread of Calvinism across Europe intensified existing religious conflicts, leading to the war which ended with the Peace of Westphalia in 1648.
Step-by-step explanation:
One of the causes of the Thirty Years' War was the aspirations of the growing Protestant sect of Calvinism (B). The Thirty Years' War, which lasted from 1618 to 1648, involved Catholic and Protestant states within the Holy Roman Empire and beyond. Calvinists, who followed the teachings of John Calvin, spread his ideology across various parts of Europe, including the Netherlands and France, adding fuel to the religious turmoil of the period.The conflict initially started as a struggle between German Catholics, Lutherans, and Calvinists. It eventually drew in other European powers, such as Sweden and France, due to strategic and religious interests. The war ended with the Peace of Westphalia in 1648, which acknowledged the independency of the entities within the Holy Roman Empire and marked the rise of France as a dominant power in western Europe.In conclusion, Calvinism played a significant role in the outbreak of the Thirty Years' War, as its expansion and influence caused increasing tensions among the existing religious factions within the empire.