You have an Azure DevOps project and an Azure subscription. You have to prevent releases from being deployed unless they comply with the Azure Policies that are assigned to the Azure subscription. Which of the following would you use for this purpose?

Answer options:

A.A pipeline variable
B.A deployment gate
C.A deployment trigger
D.A deployment approval

Answer – B 
In Azure Pipelines, you can define a gate that can ensure the deployment complies with Azure Security policies. When defining a gate in Azure Pipelines, you can actually use the “Security and Compliance assessment task” to check for compliance with Azure Policies. 
Since this is clearly given in the Microsoft documentation, all other options are incorrect. 
For more information on complying with Azure policies for your pipelines, you can refer to the below link- 

https://docs.microsoft.com/en-us/azure/devops/pipelines/policies/azure-policy?view=azure-devops