You need to recommend a procedure for closing the Brussels office that meets the technical...

In the main office, deploy an Exchange Server 2016 server that has the Unified Messaging role installed, and then move the mailboxes from the Brussels office to the new server.

Deploy a Microsoft Skype for Business 2019 server to the main office, and then move the mailboxes from the Brussels office to an Exchange Server 2019 server in the main office.

Implement a new mailbox database on an Exchange Server 2019 server in the main office, and then move the mailboxes from the Brussels office to the new mailbox database.

Implement a new database availability group (DAG) that contains the server in the Brussels office and a new Exchange Server 2019 server in the main office, and then create a mailbox database copy on the new server in the main office.