The configuration information of the G0/0/1 port of the switch is as follows. Which VLAN data frame does the switch forward not carry the VLAN TAG?
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interface GigabitEthernet0/0/1
port link-type trunk
port trunk pvid vlan 10
port trunk allow-pass vlan 10 20 30 40
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A . 10
B . 30
C . 40
D . 20
Answer: A