Which of the following treaties was instrumental in establishing the European Union (EU)?

Treaty of Maastricht

The correct answer is Option (3) → Treaty of Maastricht

The Treaty on European Union, commonly known as the Treaty of Maastricht, was signed in 1992 and came into force in 1993. It formally created the European Union, which was built upon the existing European Communities. The treaty also laid the groundwork for a common currency (the Euro) and increased cooperation among member states in areas like foreign policy, security, and justice.