In the European Union, Which of the Following Is the Source

Multiple Choice

In the European Union, which of the following is the source to turn to, in order to understand how the various member states regulate contracts?

A) The Principles of European Contract Law
B) The European Union Contract Manual for Member States
C) The Elements of Contractual Relation in the European Union
D) European Contract Law
E) None of these because all the member states have their own individual regulations