Which of the following countries operates an unwritten constitution?

Great Britain operates an unwritten constitution. An unwritten constitution is a system of government that has no written constitution or codified laws. It is based on a set of traditions, customs, and practices that have evolved over time. Great Britain has a parliamentary system of government that is based on the principles of parliamentary supremacy, the rule of law, and the separation of powers. The UK's constitution is made up of various sources including statutes, case law, and conventions.