Under Article 62 VCLT, the doctrine of REBUS SIC STANTIBUS permits a State to invoke FUNDAMENTAL CHANGE OF CIRCUMSTANCES as a ground for terminating or withdrawing from a treaty IF:

1. Article 62(1) VCLT codifies REBUS SIC STANTIBUS very narrowly: 'A fundamental change of circumstances which has occurred with regard to those existing at the time of the conclusion of a treaty, and which was not foreseen by the parties, may not be invoked as a ground for terminating or withdrawing from the treaty UNLESS: (a) the existence of those circumstances constituted an essential basis of the consent of the parties to be bound by the treaty; and (b) the effect of the change is radically to transform the extent of obligations still to be performed under the treaty.' 2. Article 62(2): the doctrine CANNOT be invoked for treaties establishing a BOUNDARY, or if the change is the result of a breach by the invoking party. 3. The ICJ in Gabčíkovo–Nagymaros Project (Hungary/Slovakia), 1997 ICJ Rep 7, applied the doctrine very strictly. 4. Hence option B is correct. _Source: UN Charter 1945 / Vienna Convention on Law of Treaties 1969 / ICJ Statute / ARSIWA 2001 — Vienna Convention on the Law of Treaties 1969, Article 62_