Apple Certified Support Professional Practice Test

System Integrity Protection (SIP) is a security feature in macOS that helps prevent potentially malicious software from modifying protected files and folders. The correct answer highlights the directories that SIP specifically protects, which include /System, /usr, /bin, and /sbin.

These directories are essential for the system's operation and contain critical system files. SIP ensures that even users with administrative privileges cannot alter the contents within these folders, thereby maintaining the integrity of the macOS environment. This protection is crucial in preventing malware from compromising system files that could potentially lead to security vulnerabilities.

The other options consist of user-specific or less critical system directories, which do not fall under the strict protections of SIP. For example, the /Users/Shared and ~/Public directories are designed for user access and sharing among different accounts, while ~/Downloads and ~/Library are typically user-specific folders where personal files and preferences are stored. The /private/var and /private/etc directories, while important for the system's operation, do not fall under the read-only protections that SIP enforces on the core system directories specified in the correct choice.