Both A and B as suggested by your are incorrect. Let's say you have three agents and a single TestList. If you schedule this TestList to run on all three machine - it will simultaneously run on all three.
I don't particularly like this implementation. We'll be introducing some major changes in the Scheduling in the near future so it's likely to change.
Also, Test Studio will give you many other benefits over the Framework apart from Scheduling.
the Telerik team