Answer:
D. maintained a set of common laws
Step-by-step explanation:
Maintaining a set of common laws was not an outcome of the European Union. The European Union was established with the aim of promoting peace, stability, and economic prosperity in Europe. It has achieved several outcomes, including easing trade barriers between member states, creating the Euro as a common currency, and negotiating trade agreements with European countries. However, while the EU has harmonized laws and regulations across its member states in various areas such as competition policy, environmental protection, and consumer protection, it has not created a uniform legal system that applies to all member states.