The reason why large areas of Russia are sparsely populated is Many areas of the country have extreme cold climates.
A lot of areas in Russia especially in Siberia are quite cold and people avoid those areas hence why there are not much people there.
The temperature in those areas also hinder human activities which leads to less people being there.
In conclusion, option C is right.
Find out more on Siberia at https://brainly.com/question/4184287.