How do Cisco routers determine their router ID (RID)?

A. The lowest IP address configured on the loopback interfaces
B. The highest IP address configured on the router
C. The lowest IP address configured on the router
D. The highest MAC address configured on the router

B. The highest IP address configured on all of the loopback interfaces is chosen first. If a loopback is not configured, then the highest IP address on an active interface is chosen. However, if a RID is statically set via the OSPF process, it will override all of the above.