About the description of Russian terrain, it is correct that () A. Russian terrain is high and steep, mainly mountainous. B the yenisei river is the plain and central part of western Siberia.

Yenisei River is the dividing line between Vera Plain in the west and Siberia Plateau in the middle, so B is correct;

The topographical characteristics of the Asian part of Russia are high in the south and low in the north, so C is wrong;

The Ural Mountains extend in the north-south direction, so D is wrong.

Therefore, choose: B.