The question of why the South African state views the global political system as fundamentally unjust, unequal, and discriminatory fits into the category of d. Ontology.
Ontology deals with the nature of being and existence, as well as the relationships and structures that define a certain reality. In this context, the South African state’s perception of the global political system revolves around its understanding of power relations, justice, and equality, which are ontological considerations regarding the nature of global politics and international relations.
While aspects of methodology, axiology (values and ethics), and epistemology (the nature of knowledge) could also be relevant in broader discussions, the core of the question emphasizes the inherent nature and structure of the global political system as viewed by South Africa, making ontology the most fitting concept.