Final answer:
b) International Law
The law often used to describe legally binding agreements of treaties is International Law. International law is a set of formal and informal rules that govern the international system and determine the conduct of state and non-state actors.
Step-by-step explanation:
The law often used to describe legally binding agreements of treaties is International Law. International law is a set of formal and informal rules that loosely govern the international system and determine the conduct of state and non-state actors. It encompasses treaties, other international agreements, and customary law derived from the practices of states. International law plays a critical role in increasing the predictability of international relations and covers various areas such as human rights, maritime law, commerce, and the environment.