The correct answer is 'Azure Policy'. Azure Policy allows you to create, assign, and manage policies that enforce different rules over your resources, ensuring that they stay compliant with your corporate standards and service level agreements. Using Azure Policy, the cloud administrator can ensure that specific monitoring agents are required on virtual machines. An 'Azure Management Group' is used for managing multiple subscriptions, but does not directly enforce policies on resources. 'Azure Resource Locks' prevent resources from being deleted or modified, but do not enforce the presence of monitoring agents. 'Azure Service Health' provides information on the health status of Azure services, but does not enforce policies on resources.