In a compacted topic, after writing a 'Tombstone' (null value) for a specific key, what mechanism prevents the record from occupying disk space forever?

1. A The record is deleted as soon as the first consumer confirms it has seen the null value.
2. B The 'Log Cleaner' thread eventually removes the tombstone after the `delete.retention.ms` period, ensuring all consumers have had time to see the deletion signal.
3. C Kafka performs a 'Force Flush' that overwrites the sector on the physical disk.
4. D The ZooKeeper coordinator manually prunes the segment indices during low-traffic periods.