Leonidas uses the standard penetration testing methodology shown here. Which of the following tools is most likely to be used during the discovery phase?

Discovery can include both active and passive techniques. Port scanning is commonly done during discovery to assess what services the target provides, and Nmap is one of the most popular tools used for this purpose. Nessus and Nikto are more often used during vulnerability scanning, and John the Ripper is used for password cracking during exploitation.