Which of the following is not one of the "Three Unities" of Drama?

In drama, the "Three Unities" are three principles derived by French classicists from Aristotle's "Poetics". They are principles that require a play to have a single action represented as occurring in a single place and within the course of a day. These principles were respectively called: unity of action, unity of time, and unity of place.

With the unities, unity of action notes that a tragedy should have only one principal action; unity of time tells us that the action in a tragedy (drama) should occur over a period of no more than 24 hours; and unity of place states that a tragedy should specifically exist in a single physical location.

These unities have been considered very important ever since the Renaissance (the period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ideas and achievements of classical antiquity). Two strong reasons for the unities exist. First, Aristotle himself had enjoined them, and secondly, they are seen as necessary to create a dramatic illusion. By operating as they do, they make drama credible and convincing.