Concept:An unwritten constitution is a constitution that is not codified into a single document.
Explanation:The term "unwritten" does not mean the constitution cannot be written at all.
It means that the fundamental rules of governance are not gathered in one single legal document.
Instead, the constitution is based on customs, conventions, statutes, and judicial decisions.
For example, in a country with such a constitution, important rules are found in different sources rather than one written text.
Therefore, the correct description is that the constitution is not contained in a single document.
Answer:A. constitution is not contained in a single document.