What should you include in the recommendation?

You have an Exchange Server organization. The organization contains servers that have Exchange Server 2010 and Exchange Server 2016 installed.
You establish a hybrid deployment between Exchange Server and Microsoft Office 365. Some users have on-premises mailboxes and personal archives in Exchange Online.
You discover that you are unable to use In-Place eDiscovery to search user mailboxes and Exchange Online Archiving archives concurrently.
You need to recommend a solution to ensure that In-Place eDiscovery can search the mailboxes and the personal archives concurrently.
What should you include in the recommendation?
A. OAuth authentication
B. an organization relationship
C. a retention policy
D. the Mailbox Replication service (MRS)