正解:C
The correct configuration to ensure that R1 is the active gateway whenever it is in a functional state for the
172.30.110.0/24 network involves setting a lower priority on R1 so that it becomes the preferred active router.
In HSRP (Hot Standby Router Protocol), the router with the lower priority value is chosen as the active router.
Additionally, preempt should be enabled on R1 to allow it to take over as the active router if it has a higher priority than the current active router.