Final answer:
Social engineering is best mitigated through proper user training as it involves manipulating individuals to compromise security. User training educates individuals on recognizing and responding to such tactics.
Step-by-step explanation:
Among the options given, social engineering is best mitigated through proper user training. Social engineering attacks include phishing, pretexting, baiting, and other tactics that rely on manipulating individuals to reveal confidential information or perform actions that compromise security. Proper user training can significantly reduce the risk of social engineering by educating users on how to recognize these tactics and how to respond appropriately.
On the other hand, worms, rootkits, and browser adware are types of malware that typically require technical controls such as antivirus, firewalls, and anti-spyware tools for mitigation. Nevertheless, user training can also help in reducing the risk of infection from these threats by teaching users safe online practices.