Final answer:
In the 10th and 11th centuries, under the early Capetian monarchs of France, feudalism was more decentralized, with noble vassals wielding significant power. However, this arrangement evolved as the French monarchy began to centralize power by the 12th century, solidifying royal control by the early 14th century.
Step-by-step explanation:
During the 10th and 11th centuries, under the early Capetian monarchs in France, the correct answer to what was true is b) Feudalism became more decentralized. Rather than centralizing, the early Capetian monarchs had limited control over their territory, and noble vassals held a significant amount of power. The early Capetian kings had very little influence outside of their own domain and the power of the nobility was substantial since the monarch's ability to enforce their rule across France was relatively weak.
It is important to note, however, that over time this began to shift, particularly by the 12th century when the French monarchy started to strengthen and centralize its power. The process of centralization and the reduction of nobility's authority continued, particularly under monarchs like King Philip II in the late 12th century. Gradually, with the convergence of military changes, demographic shifts like the Black Death, and economic transformations, the landscape of power began to change, laying the groundwork for the modern nation-state. By the early 14th century, France was increasingly under direct royal control.