Which of the following was not an original feature of the U.S. constitutuion?

To accurately answer your question, I would need to know the specific features you are referring to. However, generally speaking, features such as the Bill of Rights, which guarantees individual liberties, were not part of the original U.S. Constitution and were added later as the first ten amendments in 1791. Other features, like the separation of powers and the system of checks and balances, were indeed part of the original Constitution.