Which secondary becomes primary if all replicas are synch'd with synchronous-commit config?

Hi All,

Question: Which secondary gets promoted to primary on auto-failover if all secondaries are synch'd and configured for automatic failover and all replicas availability modes are set to "synchronous commit?"

I'm a complete beginner to AlwaysOn and don't have a server cluster on which to practice.  I've read, re-read, and re-re-read the 70-462 book chapter on AlwaysOn, but I still have a few basic questions, and this is the leading one.  How does SQL Server decide which secondary replica should be promoted [hopefully I'm using the proper terminology here] to primary if all secondary replicas are in an identical state?

Could I test AlwaysOn with Hyper-V instances?  To date, I've assumed it requires multiple machines to make a server cluster.  The book's a bit vague on this.

Thanks,
Eric B.