Final answer:
The router ID will be the highest IP address of all active interfaces, given no manually configured router ID or higher IP address present on a loopback interface.
Step-by-step explanation:
The question pertains to the selection process of the router ID in networking protocols. To clarify, the router ID is an IP address value used to uniquely identify a router within an autonomous system. The selection process of the router ID follows a specific order. First, if a router ID is manually configured, that ID will be used. If no manual configuration is found, the router will select the highest IP address of any configured loopback interface. If no loopback interface is configured, the highest IP address of all active router interfaces will be chosen. Therefore, the correct answer is:
c) The highest IP address of all active interfaces
However, this assumes there is no configured router ID and no loopback interfaces are present. If a network has multiple loopback interfaces, the IP address of Loopback0 or Loopback1 will be preferred if either has the highest IP address compared to all other interfaces.