The administrator wants to configure the OSPF route priority value to be 100 on the MSR router. Which of the following commands is correct?

Regarding the Tpe4 LSA in the OSPF protocol, the correct statement is ______

In the topology shown in the figure, the following configurations are performed on RTA, RTB, RTC and RTD respectively:
RTA] ospf 1 router-id 1.1.1.1
RTA-ospf-1] area 0
RTA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
RTA-ospf-1-area-0.0.0.0] network 1.1.1.1 0.0.0.0
RTB] ospf 1 router-id 2.2.2.2
RTB-ospf-1] area 0
RTB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
RTB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0
RTB-ospf-1] area 1
RTB-ospf-1-area-0.0.0.1] network 192.168.2.0 0.0.0.255
RTB-ospf-1-area-0.0.0.1] vlink-peer 3.3.3.3
RTC] ospf 1 router-id 3.3.3.3
RTC] ospf 1] import direct
RTC-ospf-1] area 1
RTC-ospf-1-area-0.0.0.1] network 192.168.2.0 0.0.0.255
RTC-ospf-1-area-0.0.0.1] vlink-peer 2.2.2.2
RTC-ospf-1] area 2
RTC-ospf-1-area-0.0.0.2] network 192.168.3.0 0.0.0.255
RTD] ospf 1 router-id 4.4.4.4
RTD-ospf-1] area 2
RTD-ospf-1-area-0.0.0.2] network 192.168.3.0 0.0.0.255
RTD-ospf-1-area-0.0.0.2] network 4.4.4.4 0.0.0.0
Then the router type in the RTC in the OSPF area is _______

Two routers cannot establish OSPF neighbor relationship. The following possible reasons are ________.

Among the following types of LSA, there must be ______ generated by ABR.