Article 2(1)(a) VCLT defines 'TREATY' as:

Question

Accepted Answer

D. an international agreement concluded between STATES in WRITTEN FORM and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation

1. Article 2(1)(a) VCLT defines 'treaty': 'an international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation'.
2. Three key elements: (i) BETWEEN STATES; (ii) WRITTEN FORM; (iii) governed by INTERNATIONAL LAW.
3. Treaties with international organisations are governed by the 1986 Vienna Convention.
4. Designations vary: treaty, convention, protocol, charter, statute, pact, agreement, accord — all are 'treaties' if they satisfy these elements.
5. 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 2(1)(a)_

Answer

any informal arrangement or memorandum of understanding between officials (cf. Vienna Convention on the Law of Treaties 1969, Article 2(1)(a)) (cf. Vienna Convention on the Law of Treaties 1969, Article 2(1)(a))

Answer

any commercial contract between a State and a foreign company (cf. Vienna Convention on the Law of Treaties 1969, Article 2(1)(a)) (cf. Vienna Convention on the Law of Treaties 1969, Article 2(1)(a))

Answer

any oral promise made by a Head of State to another Head of State (cf. Vienna Convention on the Law of Treaties 1969, Article 2(1)(a)) (cf. Vienna Convention on the Law of Treaties 1969, Article 2(1)(a))