Final answer:
The Eastern Roman Empire's stability was primarily due to its geographic advantages, which facilitated defense and trade, in addition to a more efficient bureaucracy and strong Roman identity among its elites and citizens. Option b.
Step-by-step explanation:
Primary Reason for Eastern Roman Empire's Stability
The primary reason for the Eastern Roman Empire's stability during the third and fourth centuries, while the Western Roman Empire faced numerous challenges, is b) Geographic advantages.
The Eastern Roman Empire, particularly its capital Constantinople, benefited from a strategic location that was well-defended, economically prosperous, and culturally rich. This location facilitated trade and defense, and kept the East closer to the economically vital regions and to the frontiers that required military attention.
Additionally, the Eastern Empire had a more efficient bureaucracy and better tax collecting systems, ensuring a steady flow of wealth into its coffers, thus enabling it to maintain a well-equipped and well-trained military. The Eastern Empire also experienced a stronger sense of Roman identity among its elites and citizens, further contributing to its unity and strength.
On the other hand, factors that made the Western Roman Empire more prone to societal disruption include its longer frontier, which was harder to defend, its less urbanized society, and the power of the rich Roman elites who undermined the authority of the western imperial government.
Option b is correct answer.