A write request arrives at the Coordinator, but one of the target Replica nodes is temporarily unreachable. The Coordinator stores a 'Hint' on its own local disk. What is the fundamental trade-off of this mechanism?

1. A It provides a 100% guarantee that the data will never be lost, even if the Coordinator node also crashes.
2. B It improves Availability: The write can still succeed despite the node outage. However, the data is essentially 'Missing' from the actual replica until the node returns and the hint is replayed.
3. C It automatically triggers a cluster-wide leader election to replace the down node within 5 seconds.
4. D It is a form of synchronous replication that forces the client to wait until the down node is rebooted.