1. The problem asks to identify the correct property of a complete graph. 2. A complete graph is a graph in which every pair of distinct vertices is connected by a unique edge. 3. Let's analyze the options: - Connected: Yes, a complete graph is connected because there is a path between every pair of vertices. - Regular: Yes, a complete graph is regular because every vertex has the same degree, which is $n-1$ where $n$ is the number of vertices. - Circuit: No, a complete graph itself is not a circuit, but it contains many circuits. - Simple: Yes, a complete graph is simple because it has no loops or multiple edges. 4. Therefore, the correct properties of a complete graph are connected, regular, and simple. Final answer: A complete graph is connected, regular, and simple.