Your network contains a server named Server1 that has System Center 2012 Virtual Machine Manager (VMM) installed.
You plan to deploy a service named Service1.
Service1 will contain three tiers.
Each tier will contain 10 instances.
You need to configure the service template to ensure that when an application in Service1 is upgraded, Service1 remains available.What should you configure for each tier?

A.
The maximum instance count

B.
The preferred servicing order

C.
The number of upgrade domains

D.
The minimum instance count

E.
The preferred deployment order

Explanation:
To minimize service interruptions when a tier is updated in-place, you can specify more than one upgrade domain in the tier properties.
When the tier is updated, VMM updates the virtual machines in the tier according to the upgrade domain to which they belong.
VMM upgrades one upgrade domain at a time, shutting down the virtual machines running within the upgrade domain, updating them, bringing them back online,
and then moving on to the next upgrade domain.
By shutting down only the virtual machines running within the current upgrade domain, VMM ensures that an upgrade takes place with the least possible impact to
the running service.
http://technet.microsoft.com/en-us/library/gg675089.aspx