Explanation:

- Classes are the strata defined on the basis of:

- Option 1: Socio-economic criteria

- Combines social and economic factors.

- Looks at how both influence and stratify society.

- Option 2: Political criteria

- Relates to divisions based on political power or influence.

- Less commonly used to define social classes.

- Option 3: Social criteria

- Focuses on norms, cultures, and societal roles.

- Can include aspects like caste systems or social status.

- Option 4: Economic criteria

- ?? Defines class based primarily on financial wealth or income.

- Commonly used to separate classes like working, middle, and upper.

Correct Answer: Option 4: Economic criteria