Which two server role sets can you use?

A company plans to deploy a SharePoint 2016 farm. The company only has enough budget to
purchase four SharePoint Server licenses and two SQL Server licenses. The farm must be highly
available. You need to deploy the SharePoint 2016 farm. Which two server role sets can you use?
Each correct answer presents a complete solution.

A.
Two front-end servers and two custom servers.

B.
Two front-end servers and two application servers.

C.
One front-end server, one application server, and two custom servers.

D.
One front-end server, one application server, one Search Server, and one Distributed Cache server.