Final answer:
The router looks for the last resort or default route when it does not find a matching entry.
Step-by-step explanation:
The correct answer is d) Last resort, default route. When a router does not find a matching entry, it looks for the last resort or default route to use.
This default route is often referred to as the last resort since it is the route that will be used if no other route is a match.
It acts as a backup option to ensure that data can still be transmitted even if no specific route is available.