Law and order can best be maintained in Nigeria through the

Law and order can best be maintained in Nigeria through constitutional law enforcement and citizens' common welfare. This means that the rule of law, as enshrined in the Nigerian Constitution, should be upheld and enforced by the security agencies. Also, citizens have a responsibility to respect the laws and cooperate with law enforcement agencies in maintaining law and order. This can be achieved through education and awareness campaigns, civic engagement, and social programs that promote peace and stability in communities. While the use of modern security gadgets and the directorate of state security service may play a role in maintaining law and order, it is important to note that the most effective approach is to have a society where everyone plays their role in upholding the law and promoting peace. Therefore, the correct option is "constitutional law enforcement and citizens' common welfare."