The suggested answer is A, C.
To improve resiliency for individual redundancy groups in an SRX4600 chassis cluster, IP address monitoring and interface monitoring are the correct features. IP address monitoring allows the system to track the availability of upstream devices and trigger failover if necessary. Similarly, interface monitoring tracks the status of physical interfaces and can initiate redundancy group state transitions if any critical interfaces go down. These features ensure that faults in the network are quickly identified and addressed, thereby improving overall resiliency.