The suggested answer is B.
If you want to scan fewer ports than the default scan using the Nmap tool, you would use the -F option. The -F flag stands for 'Fast mode' and instructs Nmap to scan fewer ports, typically focusing on the most common 100 ports, instead of the default 1000 ports. This allows for a quicker scan which can be useful when time is a critical factor or when a quick overview of the network’s most common open ports is desired.