Final answer:
Azure Resource Manager is a service that enables users to manage their Azure resources collectively, offering a way to deploy, update, and delete resources efficiently and securely.
Step-by-step explanation:
The answer to the given question is A. Azure Resource Manager. Azure Resource Manager is a management layer that allows users to create, update, and delete resources in their Azure account. You can manage your infrastructure through declarative templates rather than scripting. By organizing resources into groups, this service can help manage the lifecycle of your solutions in a coordinated way, applying permissions at the group level for multiple resources simultaneously, and ensuring consistent resource deployment.