Concept:A state is a political organisation created mainly to ensure order and security in a defined territory.Explanation:Among the given options, the basic and most fundamental purpose of a state is to maintain law and order.Without internal peace and security, no other aim such as development or social facilities can be achieved.The state also protects its citizens and defends its territory from attacks, but its core reason for existence is establishing and enforcing order.Answer:A. maintain law and order