Explanation:
Box 1: No
Authorization to access Azure resources can be provided by other identity providers by using federation. A commonly used example of this is to federate your on-premises Active Directory environment with Azure AD and use this federation for authentication and authorization.
Box 2: Yes
As described above, third-party cloud services and on-premises Active Directory can be used to access Azure resources. This is known as `federation'.
Federation is a collection of domains that have established trust. The level of trust may vary, but typically includes authentication and almost always includes authorization. A typical federation might include a number of organizations that have established trust for shared access to a set of resources.
Box 3: Yes
Azure Active Directory (Azure AD) is a centralized identity provider in the cloud. This is the primary built-in authentication and authorization service to provide secure access to Azure resources.
References:
https://docs.microsoft.com/en-us/azure/active-directory/hybrid/whatis-fed
https://docs.microsoft.com/en-us/azure/active-directory/develop/authentication-scenarios