Answer:
Social mobility relates to stratification because social stratification is the hierarchical arrangement of society, while social mobility is a person(s) ability to change position in society's hierarchical arrangement.
The amount of social mobility in a society depends on the type of stratification system. There are two types of stratification systems: ascription-based and achievement-based. In an ascription-based stratification system a person's class is based on characteristics they are born with. This is what is considered a closed society.There is little-to-no social mobility because you have no control over your birth. In an achievement-based stratification system a person's rank is based on a person's accomplishments. This is what is considered an open society. People have the ability to move up the social ladder through natural talents, or by learning skills.