Your company hosts an Azure API that needs to authenticate to other Azure resources. Requirements: every API call must be authenticated, and API callers must not send credentials to the API. Which authentication mechanism meets these requirements?

Managed identities for Azure resources provide an automatically managed identity in Azure Active Directory (Azure AD) for applications to use when connecting to resources that support Azure AD authentication. This eliminates the need for developers to manage credentials, as Azure handles the lifecycle of the identity. Since the identity is managed by Azure and associated with the resource (like an Azure API App), the API itself doesn't need to receive credentials from the caller to authenticate to other Azure resources. Basic authentication involves sending credentials (username/password) with each request, which is explicitly against the requirement. Anonymous access means no authentication occurs. Client certificates require the API caller to manage and send a certificate, which is a form of credential management that the requirement aims to avoid.