Final answer:
The two motives for Russian expansion from 1500-1800 C.E. were to secure access to warm-water ports for trade and military purposes, and to establish a buffer against invasions for enhanced security. The strategic expansion aimed to solidify Russia's standing as a world power. The correct option is D.
Step-by-step explanation:
The two motives that drove Russian expansion between 1500-1800 C.E. were primarily focused on access to warm-water ports and security against invasions. The expansion was part of an overarching strategy to establish Russia as a great world power through territorial gains. The move towards the Pacific Ocean, the acquisition of lands by Peter the Great and Catherine the Great on the Baltic and Black seas, and the territorial expansion into Central Asia under later tsars, were largely driven by these strategic concerns.
It was not merely about gaining land; these were areas with strategic importance for trade, military, and political influence. Especially for Russia, with its harsh winters, access to warm-water ports was crucial for year-round trade and maintaining a strong navy.
The need for security was also a significant factor; for instance, Russian leaders were aware of the importance of territorial expansion as a buffer against potential invasions from Western and Eastern powers. While there were also undercurrents of economic envy due to Russia's natural resources, concerns about autocratic governance, and efforts to modernize the country, these did not manifest as the primary drivers for expansion, which was more connected to strategic military and political dominance.
Hence, Option D is correct.