Question

In _____ mobility, many people move up the social class ladder, and many move down, with the social class system showing little change.

Answer 1

I believe the answer is: Exchange mobility
In exchange mobility, the society is divided into several classes, but the member of each classes is expected to remain static.
So, if a members in this society intended to move up in social ladder, other member has to move down in social ladder and be replaced.