What is one benefit of PVST+?

A.
PVST+ supports Layer 3 load balancing without loops.

B.
PVST+ reduces the CPU cycles for all the switches in the network.

C.
PVST+ allows the root switch location to be optimized per VLAN.

D.
PVST+ automatically selects the root bridge location, to provide optimized bandwidth usage.

Explanation:
Per VLAN Spanning Tree (PVST) Introduction
http://www.cisco.com/en/US/tech/tk389/tk621/tk846/tsd_technology_support_subprotocol_home.html
Per VLAN Spanning Tree (PVST) maintains a spanning tree instance for each VLAN configured in the
network. This means a switch can be the root bridge of a VLAN while another switch can be the root
bridge of other VLANs in a common topology. For example, Switch 1 can be the root bridge for Voice
data while Switch 2 can be the root bridge for Video data. If designed correctly, it can optimize the
network traffic. http://www.ciscopress.com/articles/article.asp?p=102157&seqNum=4