You are an IT-administrator in your company. The organization`s lawyer is leaving the company. You must make sure his mailbox is retained for 15 years as it might contain important information needed later. After 15 years the mailbox should be deleted automatically. You are also to remove his Office 365 licenses. 
What should you do?Choose two options.

Answer options:

A.Block the user account.
B.Delete the user account.
C.Assign a retention policy.
D.Enable mailbox archive on the user mailbox.
E.Create an identity protection policy.

Correct Answers: B and C 
You should assign a retention policy on the mailbox to retain the content for 15 years. After the policy is applied you should delete the user to free up the license.
Option A is incorrect. Blocking the account will prevent the user from logging on to Office 365, but it will not remove his licenses. 
Option D is incorrect. Enabling the archive on the user mailbox is not correct. If you delete the user or manually remove his licenses, the associated archive will also be marked for removal. 
Option E is incorrect. Creating an identity protection policy is not relevant in this scenario.
Reference: 
To know more about retaining inactive mailboxes, please refer to the link below: 

https://docs.microsoft.com/en-us/microsoft-365/compliance/inactive-mailboxes-in-office-365?view=o365-worldwide