Answer: Consolidate its various Law Codes
Step-by-step explanation:
The European Union is a Union between the member states of Europe that binds them politically and economically.
Countries in the EU have already consolidated currency for the most part as they use the Euro currency so the second option cannot be correct.
There are also no passport restrictions as there is free movement of EU citizens to any EU country so the third option is wrong as well.
EU countries already do not have tariffs amongst member states so the last option is wrong as well.
Most likely option is therefore the first one.