If you want to only scan fewer ports than the default scan using Nmap tool, which option would you use?

-r instructs Nmap to scan ports in sequential numerical order rather than randomized order, which changes scan sequence but does not reduce the number of ports scanned.

The -F (fast mode) flag instructs Nmap to consult only the top 100 entries in the nmap-services file rather than scanning the default 1000 most common ports, directly fulfilling the requirement to scan fewer ports than the default. It is the purpose-built option for reducing scan scope quickly.

-P alone is not a valid standalone Nmap flag for reducing port count; port range selection uses -p, and ping probe control uses -Pn or -P0, none of which limit the number of ports scanned.

-sP (superseded by -sn) performs a ping sweep for host discovery only and does not conduct any port scanning at all.