Article 253 of the Indian Constitution grants the Parliament the power to make laws for the whole or any part of India for implementing any treaty, agreement, or convention with any other country or countries or any decision made at any international conference, association, or other body.
This highlights the Parliament's exclusive competency to legislate on matters necessary for fulfilling international obligations, even if those matters fall within the State List.
In this context, Article 253's provision aligns with the correct answer, which states that the competency to make laws for implementing international treaties is vested with the Parliament.