Which of the following services must you manually start before Windows can apply AppLocker policies?

The correct answer is the Application Identity service. This service is crucial because AppLocker, which is designed to enforce application control policies, relies on it to determine the identity of applications and their associated files. Before Windows can effectively apply any AppLocker policies, the Application Identity service must be running.

When this service is not started, AppLocker policies will not be enforced, regardless of how well they are configured in Group Policy. This is important for system administrators to understand when setting up application control, as failing to start this service can lead to security gaps where potentially harmful applications might be executed.

In contrast, while other services such as Group Policy Client or Windows Event Log play essential roles in the overall function of a Windows system, they do not specifically tie into the enforcement mechanism of AppLocker policies. The Security Accounts Manager is responsible for managing user accounts and security policies but is unrelated to the implementation of AppLocker functionalities. Therefore, understanding the dependency of AppLocker policies on the Application Identity service is critical for effective application control management in Windows Server environments.