You need to assign permissions so that a particular user can add the agent machines to an agent pool. You need to ensure that you provide the least privilege required. Which of the following would you consider assigning to the user?

Answer options:

A.Reader
B.Contributor
C.Service Account
D.Administrator

Answer – D 
This can only be accomplished via the Administrator role. The Microsoft documentation mentions the following when it comes to the security of agent pools. 

Since this is clearly given in the documentation, all other options are incorrect. 
For more information on agents for Azure pipelines, please visit the below URL- 

https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/pools-queues