Explanation:

- Informally: In agrarian societies, sanctions are often imposed informally. Social norms and customs dictate behavior, and community members enforce these through social pressure and ostracism.

- Through law: Formal legal systems may be less developed in agrarian societies. Laws might exist, but informal mechanisms are more prevalent for social control.

- Through constitutions: Constitutions imply a formal legal framework, which is usually not a characteristic of early agrarian societies. They may have rules, but not a formal constitution.

- Through police: Formal police forces are not typically present in traditional agrarian societies. Social order is maintained informally by community members.