Which treaties marked the full European integration in the social sphere?

The Maastricht Treaty and the Lisbon Treaty are indeed pivotal in the context of European integration, especially regarding the social sphere. The Maastricht Treaty, signed in 1992, founded the European Union and established the framework for expanded cooperation in various areas, including social policy. It introduced the concept of European citizenship and set the groundwork for enhanced collaboration on employment, labor rights, and social inclusion.

The Lisbon Treaty, which came into force in 2009, further deepened the integration by enhancing the role of the European Parliament and consolidating various treaty provisions related to social policies. It introduced the Charter of Fundamental Rights of the European Union, which enshrines important social rights and has a direct effect across member states, strengthening the legal basis for social protection, equality, and workers' rights.

These two treaties collectively mark a significant step towards comprehensive integration in the social sphere within the EU, shaping the policies and legal frameworks that govern social and labor issues across member states. Other options, while they may pertain to various aspects of European integration, do not hold the same level of significance in the social domain as the Maastricht and Lisbon Treaties do.