The following four Directive Principles of State Policy are included in the Constitution of India to promote international peace and security:
1. Promotion of International Peace and Security (Article 51): The Constitution directs the State to work towards fostering international peace and security by promoting harmony and goodwill between nations.
2. International Cooperation (Article 51): India is committed to fostering respect for international law and obligations to foster peace and cooperation between states.
3. Support for the United Nations (Article 51): The State is directed to make efforts to strengthen the United Nations and promote peace through multilateral diplomacy.
4. Combating Aggression (Article 51): India aims to work towards preventing aggression and securing global stability by supporting peacekeeping efforts and multilateral security initiatives.
Thus, the correct answer is (a).