Which security measure involves regularly updating software to fix vulnerabilities?

The correct answer is patching, as this practice specifically refers to the process of applying updates to software in order to address and fix known vulnerabilities. Software vendors frequently release updates or patches that resolve security flaws, improve functionality, or enhance performance. Regularly implementing these patches is crucial in maintaining the security posture of systems and applications, helping to protect against potential exploits that attackers may leverage to gain unauthorized access or cause harm.

Monitoring, while essential for identifying suspicious activities or breaches in real time, does not directly address the issue of vulnerabilities in software. Data encryption involves converting data into a secure format that can only be read by someone with the appropriate key; this is about protecting data rather than fixing software vulnerabilities. Auditing involves examining and evaluating security measures and controls but does not itself involve updating software vulnerabilities. Thus, patching is the key action here to ensure that systems remain secure against known threats.