The correct answer is B) climate.
What accounts for the low population density found in much of Russi is the climate.
Specifically, the eastern part of Russia has low population density because the weather is cold, and during the winter season is extremely cold in the region of tundra subarctic zones. Most people live in the western part of Russia, in the region of Moscow where the weather conditions are more benevolent compared with the northeastern portions conditions that make it difficulted for people to live there.