The stratification of parent material (heterogeneous parent material) has a more complex influence on the material migration and soil fertility, compared with homogeneous parent material. The stratification of parent material will be inherited to soil.

All the societies attach the same importance to the social stratification on the basis of family background, occupation and imcome.

The Prime Minister wants to reduce social ( ) and make the country a classless society. A: stratification B: satisfaction C: education D: communication