You are a global admin in a company with a Microsoft 365 subscription and Microsoft 365 E5 licenses assigned to your users. You have set up several retention policies and labels. Due to rules defined by regulatory bodies you need to make sure one specific policy cannot be turned off, deleted or made less restrictive. 
What should you configure? 

Answer options:

A.Azure Resource Group - Locks
B.Litigation Hold
C.Azure DevOps release pipeline
D.Preservation Locks

Correct Answer: D 
You should configure a preservation lock on the policy that must be protected. This will ensure that it cannot be changed, deleted or turned off. 
Set-RetentionCompliancePolicy -Identity "<Name of Policy>" –RestrictiveRetention $true
Option A is incorrect. This feature prevents deletion of resource groups.
Option B is incorrect. This service places a mailbox on hold for a specified timeframe.
Option C is incorrect. Azure DevOps release pipelines are used for releasing a built artifact to for instance Azure. 
Reference: 
To know more about preservation locks, please refer to the link below: 

https://docs.microsoft.com/en-za/microsoft-365/compliance/retention-preservation-lock?view=o365-worldwide