An administrator needs to verify what ports are listening on an operating system. Which of the following tools can be used to accomplish this task?

`telnet` is primarily used to establish a connection to a remote host and port, not to list all listening ports on the local system.

The `netstat` command-line utility displays network connections, routing tables, interface statistics, and, crucially, lists all listening ports on a system. It provides details such as the protocol, local address (including port number), foreign address, and the state of the connection or listener.

A packet sniffer captures network traffic passing through an interface but does not directly show which ports are actively listening on the local operating system.

`ifconfig` (or `ip` on Linux) is used to configure and display network interface parameters, such as IP addresses and MAC addresses, not to list listening ports.