单项选择题
() are the products of wind erosion to the rock protruding from the ground. Since there are more sands in the lower part of the rock, the degree of abrasion is relatively higher than that of the upper part. Therefore, the rock is shaped into a mushroom with such a kind of abrasion.
A.A. wind-eroded habitacle
B.B. mushroom rocks
C.C. deflation hollow
D.D. sand dune