Would the Azure Hybrid Benefit for Windows Server allow a customer to use his existing on-premises Windows Server licenses?

Answer options:

A.Yes
B.No

Answer – A 
They can make use of the Azure Hybrid Benefit to use the user`s existing on-premises Windows Server Licenses. 
The Microsoft documentation mentions the following. 

For more information on the Hybrid Benefit model, please visit the below URL- 

https://docs.microsoft.com/en-us/azure/virtual-machines/windows/hybrid-use-benefit-licensing