Which of the following parameters enables NMAP's operating system detection feature?

`-sV` enables service and version detection, probing open ports to determine what application and version is running, not the OS.

`-oS` is an output format option that saves results in a 'script kiddie' stylized text format and has nothing to do with OS detection.

`-sR` was a legacy RPC scan method in older Nmap versions and does not perform operating system detection.

The `-O` flag instructs Nmap to perform OS detection by analyzing responses to a series of specially crafted TCP, UDP, and ICMP probes and comparing them against Nmap's OS fingerprint database to identify the target operating system and version.