What does User Account Control (UAC) do in Windows operating systems?

User Account Control (UAC) is a critical security feature in Windows operating systems designed to prevent unauthorized changes to the system. When an application or process tries to make changes that require administrative access, UAC prompts the user for permission. This helps mitigate the risk of malware and untrusted applications from making alterations to the system without the user's knowledge or consent.

The mechanism of prompting users for consent or administrative credentials acts as a protective barrier, discouraging unauthorized modifications that could compromise the system's integrity or security. By enforcing these prompts, UAC ensures that users remain aware of significant changes happening to their computer, thus fostering a more secure user environment.

Other options do not accurately reflect the primary function of UAC. While managing application installations or optimizing disk space may be relevant to system management, they do not capture the essential role of UAC in safeguarding against unauthorized system changes.