You have an Azure DevOps project that contains a build pipeline. The pipeline builds a container image named testimage and pushes the image to the Azure Container registry. The image uses a base image that is stored in Docker Hub. You have to ensure that testimage is updated automatically whenever the base image is updated. Which of the following can you implement for this requirement?

Answer options:

A.Use the Azure Container Registry task.
B.Use a Docker Hub service connection in Azure Pipelines.
C.Use Azure Event Grid and subscribe for registry events.
D.Use a service hook in the DevOps project.

Answer – A 
You can use the Azure Container Registry task to check for updates to the base image. The ACR task can be triggered automatically when there is a change to the base image. 
Options B and D are incorrect because here we just don’t need a connection or just a hook onto Docker Hub. 
Option C is incorrect because Azure Event Hub will look at changes in Azure resources. 
For more information on Azure Container Registry tasks, you can refer to the below link- 

https://docs.microsoft.com/en-us/azure/container-registry/container-registry-tasks-overview