A senior technician requests a diagnostic tool for checking external ports and connectors on computers and laptops. Which of the following tools would BEST accomplish this task?

A wireless locator is used to detect wireless networks or devices, not to test physical ports.

A corona wire is an internal laser printer component that charges the drum; it has no role in port diagnostics.

A toner probe is used to trace cable runs and locate wiring, not to test external port functionality.

Loopback plugs connect a port's output pins directly to its input pins, allowing diagnostic software to verify the port is transmitting and receiving signals correctly. They are specifically designed for testing serial, parallel, USB, and network ports on computers and laptops. No other tool in this list is designed for port-level hardware diagnostics.