A. The output displays all OSPF messages which router R1 has sent to received on interface Fa0/1.
B. The output displays all OSPF messages which router R1 has sent or received on all interfaces.
C. The output displays OSPF hello messages which router R1 has sent received on interface Fa0/1.
D. The output displays OSPF hello and LSACK messages which router R1 has sent or received.