What should you do first?

You have a Microsoft Exchange Server hybrid deployment that contains Exchange 2013, Exchange 2016, and Exchange 2019 servers. All the servers have the latest Cumulative Updates (CUs) applied. You need to implement Hybrid Modern Authentication (HMA). The solution must minimize costs.

What should you do first?
A . Upgrade the Exchange 2013 servers to Exchange 2016 CU7.
B . Add the on-premises web service URLs as Azure Active Directory (Azure AD) service principal names (SPNs).
C . Upgrade all the servers to Exchange 2019.
D . Create an Azure Active Directory (Azure AD) conditional access policy for Exchange Online.

Answer: B

Explanation:

Reference:

https://docs.microsoft.com/en-us/microsoft-365/enterprise/configure-exchange-server-for-hybrid-modern-authentication?view=o365-worldwide#make-sure-you-meet-all-the-prerequisites

https://docs.microsoft.com/en-us/microsoft-365/enterprise/hybrid-modern-auth-overview?view=o365-worldwide#do-you-meet-modern-authentication-prerequisites