In what situation must spanning-tree be implemented?

In what situation must spanning-tree be implemented?
A . When redundant Layer 2 links, that are not part of a single EtherChannel or bundle, exist between distribution switches
B . When redundant Layer 3 links, that are not part of a single EtherChannel or bundle, exist between distribution switches
C . Between Distribution and Core switches when interfaces are configured with "no switchport"
D . Between Distribution and Core switches when VSS is configured

View Answer

Answer: A