Which NMAP option enables OS detection?

• A. -O
• B. -sV
• C. -A
• D. -p

Answer: (A)

OS detection in Nmap works by fingerprinting the target’s TCP/IP stack and comparing responses to a database to infer the operating system. The option that enables this mode is -O, which tells Nmap to perform OS detection and report what it believes the host is running. The -sV option focuses on identifying service versions rather than the OS. The -A option is an aggressive scan that includes OS detection along with version detection, scripts, and traceroute, but -O is the direct, dedicated way to request OS information. The -p option simply selects which ports to scan.