How are rank and class systems different from the divisions into bands, tribes, and chiefdoms?

How are rank and class systems different from the divisions into bands, tribes, and chiefdoms?
 
  a. Rank and class systems are based on social differences and variation, while bands, tribes, and chiefdoms are based on locality.
  b. Rank and class systems are based on inequalities in resources and power, while bands, tribes, and chiefdoms are based entirely on differences in modes of subsistence and lifestyle.
  c. Rank and class systems are based on different political systems, while bands, tribes, and chiefdoms are based on social differences.
  d. Rank and class systems are based on inequalities in resources and power, while bands, tribes, and chiefdoms are based on political differences.