A. GE-1/2 and GE 2/1
B. GE-1/1 and GE-2/2
C. GE-3/2 and GE 4/1
D. no ports are in the blocking state
E. There is not enough information to determine which ports are in the blocking state.

A.The originator of the TCN immediately floods this information through the network.
B.The TCN propagation is a two step process.
C.A TCN is generated and sent to the root bridge.
D.The root bridge must flood this information throughout the network.