A. 1） lowest root bridge id，2）lowest sender bridge id，3）lowest port id，4）lowest root path cost
B. 1） lowest root path cost，2）lowest root bridge id，3）lowest sender bridge id，4）lowest sender port id
C. 1） lowest root bridge id，2）lowest sender bridge id，3）lowest root path cost 4）owest sender port id
D. 1） lowest root bridge id，2）lowest root path cost，3）lowest sender bridge id，4）lowest sender port id

A. VTP updates are ignored and forwarded out all ports.
B. VTP updates are ignored and forwarded out trunks only.
C. VTP updates are made to the VLAN database and are forwarded out trunks only.
D. VTP updates are ignored and are not forwarded.