Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Multilateral treaties which declare the established customary international law may bind even non-parties.
Reason R: Article 38 of the Vienna Convention makes an exception to Article 34 or 37 of the Vienna Convention.
In the light of the above statements, choose the most appropriate answer:

Correct option is A

Article 38 of the Vienna Convention states that a rule set forth in a treaty becomes binding as customary international law even for non-parties if it is recognized as such. Hence, both A and R are correct, and R explains A.