Which of the following commands can be used for port scanning?

The nc -z flag activates zero-I/O mode in Netcat, where it connects to a port to determine if it is open without sending or receiving any data. This makes it functionally equivalent to a basic port scan, allowing a user to quickly sweep a range of ports - for example, nc -z host 20-80 - to identify listening services.

nc -t enables TELNET protocol negotiation in the connection, which is unrelated to port scanning.

nc -w sets a timeout in seconds for idle connections, controlling how long Netcat waits before giving up, not performing a port scan.

The character shown is a corrupted or invalid argument and does not correspond to any recognized Netcat flag.