While logged into a Company switch you issue the following command:
CompanySwitch(config-mst)# instance 10 vlan 11 -12
What does this command accomplish?

A.
It enables a PVST+ instance of 10 for vlan 11 and vlan 12

B.
It enables vlan 11 and vlan 12 to be part of the MST region 10

C.
It maps vlan 11 and vlan 12 to the MST instance of 10.

D.
It creates an Internal Spanning Tree (IST) instance of 10 for vlan 11 and vlan 12

E.
It create a Common Spanning Tree (CST) instance of 10 for vlan 11 and vlan 12

F.
It starts two instances of MST, one instance for vlan 11 and another instance for vlan
12.

Explanation:
MST extends the IEEE 802.1w rapid spanning tree (RST) algorithm to multiple spanning
trees. This extension provides both rapid convergence and load balancing in a VLAN
environment. MST converges faster than Per VLAN Spanning Tree Plus (PVST+) and is
backward compatible with 802.1D STP, 802.1w (Rapid Spanning Tree Protocol [RSTP]), and
the Cisco PVST+ architecture.
MST allows you to build multiple spanning trees over trunks. You can group and associate
VLANs to spanning tree instances. Each instance can have a topology independent of other
spanning tree instances. This architecture provides multiple forwarding paths for data traffic
and enables load balancing. Network fault tolerance is improved because a failure in one
instance (forwarding path) does not affect other instances.
Map the VLANs to an MST instance.
If you do not specify the vlan keyword, you can use the no keyword to unmap all the VLANs
that were mapped to an MST instance.
If you specify the vlan keyword, you can use the no keyword to unmap a specified VLAN
from an MST instance.
Switch(config-mst)# instance instance_number vlan vlan_range
Reference:
http://www.cisco.com/en/US/products/hw/switches/ps663/products_configuration_guide_cha
pter09186a00800dde9e.html#36881