What indicates that data is actively transmitted across the cable?

The flashing of the Actively LED indicates that data is actively transmitted across the cable. This LED is designed to provide a visual cue about the state of the network connection. When data packets are being sent and received, the LED will blink or flash intermittently, reflecting the ongoing transfer of information. This is a standard feature in network devices, allowing users or administrators to quickly assess network activity at a glance.

In contrast, a steady glow of the Link LED typically means that a physical connection is established between devices, but it does not guarantee that data is actively being transmitted. A beep from the network device is often used for alerts or notifications rather than indicating data transmission. Lastly, the absence of any lights on the port typically means there is no connection or activity at all, further reaffirming that the correct choice showcases active data transmission rather than inactivity.