Article 53 of the UN Charter, in conjunction with Article 2(4), recognises one principal CHARTER-BASED EXCEPTION to the prohibition of force:

1. Article 2(4) UN Charter prohibits threat or use of force. 2. The Charter recognises TWO exceptions: (i) Article 51 — individual or collective self-defence after an armed attack; (ii) Chapter VII (Article 42) — SC enforcement action including authorisation of military measures. 3. Article 53(1): 'The Security Council shall, where appropriate, utilize such regional arrangements or agencies for enforcement action under its authority. But no enforcement action shall be taken under regional arrangements or by regional agencies without the authorization of the Security Council...' 4. UNILATERAL humanitarian intervention without UNSC authorisation is highly controversial and not generally accepted (cf. Kosovo 1999 NATO operation — politically tolerated but doctrinally contested). 5. The 'Responsibility to Protect' (R2P) doctrine adopted in the 2005 World Summit Outcome Document allows international intervention through the UNSC in cases of genocide, war crimes, ethnic cleansing, and crimes against humanity. 6. Hence option B is correct. _Source: UN Charter 1945 / Vienna Convention on Law of Treaties 1969 / ICJ Statute / ARSIWA 2001 — UN Charter 1945, Articles 2(4), 51, 53_