For the following ports， which port is on every bridge in a Spanning Tree Protocol IEEE 802.1w network except the root bridge？（）

A.For each such address and mask /32, one label binding is created.
B.As the TCP endpoint, IP addresses are used by the LDP session.
C.These addresses are used to find the label binding to put in the LFIB, by looking up these IP addresses in the routing table.
D.These addresses are used for penultimate hop popping (PHP) when forwarding packets to the next router directly. 

A.highest-numbered IP interface
B.MAC address
C.device uptime
D.root port cost