What does the --reason option do and why would you enable it?

• A. --reason prints the reason a port is in its stated state; helps interpret results, especially when states are ambiguous.
• B. --reason enables real-time network kinematics.
• C. --reason filters out ports by reason codes.
• D. --reason toggles verbose output.

Answer: (A)

The option is about showing why Nmap classified a port in a particular state. Enabling it adds a reason for each port’s state, so you can see the underlying cause—like a firewall filter or a specific type of response—that led to labels such as open, closed, or open|filtered. This makes results much easier to interpret, especially when the state is ambiguous or influenced by intermediate devices. It’s not about kinematics, filtering by reason codes, or simply increasing verbosity, which is why those other ideas don’t fit.