The correct options are
A Promote international peace and security.
C Maintain just and honourable relations between nations.
D Foster respect for international laws & international organisations.
Article 51 in the Constitution of India has four major aims. First is to promote international peace and security. The second aim is to maintain just and honourable relations between nations. The third aim is to foster respect for international laws & international organisations, and the fourth aim is to encourage settlement of international disputes by arbitration or negotiations.