Which statement is correct about the Common Spanning Tree?

A. CST elects a root bridge for each VLAN.
B. CST elects a single root bridge for the entire physical network.
C. CST has an immediate convergence because it elects a single root bridge.
D. CST is best implemented for really large networks since it scales efficiently.

B. Common Spanning Tree elects a single root bridge for the entire network and all of the VLANs. This creates a problem when the center of your network may vary upon VLAN placement.