While the meaning of constitutional guaranties never varies, the scope of their application must expand or contract to meet the new and different conditions which are constantly coming within the field of their operation. In a changing world it is impossible that it should be otherwise. But although a degree of elasticity is thus imparted, not to the meaning, but to the application of constitutional principles, statutes and ordinances, which, after giving due weight to the new conditions, are found clearly not to conform to the Constitution, of course, must fall.

--Supreme Court Justice George Sutherland, 1926

Which Constitutional principle is illustrated in these comments from Justice Sutherland?

A) that the Constitution is based on the concept of popular sovereignty
B) that the most important feature of the Constitution is the "Elastic Clause"
C) that the most important feature of the Constitution is the "Supremacy Clause"
D) that the Constitution is a "living document" that can change when the need arises

The Constitution is a document that is the base of all of the laws, the Constitution must have a more difficult way of being changed than other laws, exactly because of its importance. But the Constitution was written differently, it was written in a way that it makes possible for it to adapt to new changes and situations without the need for amendments. This ability of adaptation is why the Constitution is considered a living document because it is always changing without changing its text directly, its interpretation changes over the centuries which makes it an incredible document.