The correct answer is option 4, Britain. While India, Pakistan, and America have documented constitutions, Britain is one of the few countries that does not have a single, written constitution. Instead, Britain relies on a collection of constitutional laws, conventions, and traditions that have developed over centuries. This system is often referred to as an "unwritten constitution" because it is not found in a single document. The British constitution is based on parliamentary sovereignty, meaning that the UK Parliament has the ultimate authority to make and pass laws. This differs from countries with written constitutions, where there is a separation of powers and a higher degree of judicial review. So, unlike India, Pakistan, and America, Britain does not have a single, codified constitution.