The most accurate assessment of the long-term implications of Ivan IV's time as ruler of the Russian Empire is:
A) Ivan IV's reign marked a period of centralization and expansion in the Russian Empire, which had lasting implications for the country's territorial growth and the development of its autocratic government.
Ivan IV, also known as Ivan the Terrible, centralized power and expanded Russian territory significantly during his reign. His establishment of autocratic rule and the expansion of the empire set the stage for future rulers and shaped the political landscape of Russia for centuries to come.