Read the following paragraph and answer the following question:

A source of law within a domestic legal system is easier to determine. Within the domestic system it is considered as something which is not too difficult a process, where one may look at the various legislation or statutes provided for, by the legislature and if there is a lacunae in the statute then decisions of the domestic courts. But, it is not so easy to pin point the sources of international law.

Which one of the following is not considered as source of International laws?

PIL

The correct answer is Option (4) → PIL