Saniya, you keep writing out questions where the answer is already given to you by the revision kit.
Is it that you:
1 want me to confirm the revision kit answer 2 don’t understand why the given answer is correct 3 are testing me to see if I could pass the exam 4 like writing out questions where you already know the answer?
In answer to the question that you have typed, my own answer would be ‘the unification of laws applicable to international trade’