What is the Cisco IOS command that is used to prevent the route of the incoming traffic from an unknown network?

What is the Cisco IOS command that is used to prevent the route of the incoming traffic from an unknown network?
A . Interface FastEthernet 0/0ip verify unicast source reachable-via any allow-default
B . Interface FastEthernet 0/0ip verify multicast source reachable-via any allow-default
C . Interface FastEthernet 0/0ip verify unicast destination reachable-via any allow-default
D . Interface FastEthernet 0/0ip verify multicast destination reachable-via any allow-default

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Answer: A