Class systems differ from slavery in several ways. Class systems allow for movement within the social structure, are economically based, are large and impersonal, and are built around income, ownership of wealth, education, occupation, and lifestyle. Which of these characteristics of class as a system is most closely tied to the defining characteristic of slavery as a system?

Most forms of slavery share these characteristics: (1) slaves are obliged to live their lives in perpetual service to their master, an obligation that only the master (or the state) can dissolve; (2) slaves are under the complete power of their masters, although the state or community may impose certain restrictions upon the master's treatment of the slave; (3) slaves are property, which may be sold or passed along as an inheritance at the master's discretion; and (4) the condition of slavery is transmitted from parent to child.

In other words, the key word here is ownership.