Final answer:
In OSPF configuration on a router, the router ID is selected by choosing the highest IP address from all active interfaces, including loopback interfaces. So, the highest IP address among loopback interfaces will become the router ID.
Step-by-step explanation:
When configuring OSPF on a router with multiple loopback interfaces, the router ID is determined by selecting the highest IP address assigned to any of the router's active interfaces, provided they are up at the time of OSPF process startup. If multiple loopback interfaces are present, the highest IP address of all loopback interfaces will be chosen. Therefore, the address that gets selected as the router ID is b) The highest IP address among loopback interfaces.