An administrator (Admin1) has the following account types: an OpenID-enabled user account, a Hotmail account, an account in contoso.com, and an account in an Azure AD tenant fabrikam.com. You plan to transfer ownership of the subscription Sub1 to Admin1 using Azure Account Center. To which accounts can ownership of Sub1 be transferred?

Azure subscriptions can only be transferred to accounts that are part of an Azure Active Directory (AAD) tenant. The contoso.com account is explicitly stated as being "in contoso.com," implying it's an Azure AD tenant. The fabrikam.com account is also explicitly stated as being "in an Azure AD tenant fabrikam.com." However, the question asks about transferring ownership to Admin1, and Admin1's fabrikam.com account is not necessarily the target for the transfer. Hotmail accounts are Microsoft accounts, not Azure AD accounts, and OpenID-enabled user accounts are generic identity providers and not directly Azure AD accounts for subscription ownership. Therefore, only the contoso.com account, which is an Azure AD account, can receive the subscription ownership transfer.