During a port scan, Mikaela found TCP port 443 open on a system. Which tool is best suited to scanning the service that is most likely running on that port?

TCP port 443 normally indicates an HTTPS server. Nikto is useful for vulnerability scanning web servers and applications and is the best choice listed for a web server. Metasploit includes some scanning functionality but is not a purpose-built tool for vulnerability scanning. zzuf is a fuzzing tool and isn't relevant for vulnerability scans, whereas sqlmap is a SQL injection testing tool.