Same environment and requirements as above. Solution: use password hash synchronization and seamless single sign-on. Does this solution meet the requirements?

No, this solution does not meet the requirement of ensuring that on-premises Active Directory is the sole authoritative source for authentication. Password hash synchronization (PHS) involves syncing password hashes to Azure AD, making Azure AD a source for authentication. Seamless single sign-on (SSO) enhances the user experience but doesn't dictate the authentication authority. To ensure on-premises AD is the sole authority, a federated identity solution like Azure AD Connect with Pass-through Authentication (PTA) or Active Directory Federation Services (AD FS) would be required. PHS explicitly makes Azure AD an authentication authority, which contradicts the requirement.