The PRECAUTIONARY PRINCIPLE in international environmental law (Rio Declaration Principle 15) provides that:

1. Rio Declaration 1992, Principle 15: 'In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.' 2. The PRECAUTIONARY PRINCIPLE reverses the traditional burden of proof — preventive action even without conclusive scientific evidence. 3. The Vellore Citizens Welfare Forum v. Union of India, AIR 1996 SC 2715, treated the precautionary principle as customary international law applicable in Indian environmental cases. 4. The principle is reflected in UNFCCC, CBD, Cartagena Protocol on Biosafety, etc. 5. Hence option B is correct. _Source: UN Charter 1945 / Vienna Convention on Law of Treaties 1969 / Geneva Conventions 1949 / ICJ Statute / UDHR ICCPR ICESCR — Rio Declaration on Environment and Development 1992, Principle 15_