What is a directed network?

A directed network is characterized by having edges that contain directional arrows, illustrating the direction of the relationship between the nodes or vertices in the network. These arrows indicate how one node influences or interacts with another, which is crucial in various applications such as traffic flow, social networks, and communication systems.

In contrast, the other options do not accurately define a directed network. A network with no edges lacks the connections needed to form a network. A diagram with undirected edges would imply that the connections are mutual and do not have a specific direction, thus failing to represent a directed network. Lastly, while a network that is not connected describes a network where some nodes cannot be reached from others, it does not inherently reflect anything about the directionality of the edges. Therefore, the defining feature of a directed network is indeed the presence of arrows on the edges, which clarify the direction of the connections.