Final answer:
The Volga River length is a physical geography characteristic of Russia, as it represents a natural feature and contributes to the country's geographical identity.
Step-by-step explanation:
Among the options provided for a physical geography characteristic of Russia, the Volga River length would be considered a physical geography characteristic. Physical geography pertains to the natural features and phenomena of a place. The Volga River, being the longest river in Europe, contributes significantly to Russia's physical geography. It serves as a major transportation network and has historically been critical to the development and sustenance of the regions through which it flows.