Message with no keys will be stored with round-robin strategy among partitions.

The ConsumerRebalanceListener lets youhandle partition assignments and revocationsduring rebalances.
This is critical for managingoffsets,stateful processing, orexternal transactions.
FromKafka Consumer Rebalance Docs:
"Implementing ConsumerRebalanceListener allows your application to take action before and after partitions are reassigned."
* A is true: It lets your app react when partitionsassigned to the consumer change.
* B, C, and D are unrelated to consumer rebalancing directly.
Reference:Kafka Consumer JavaDocs > ConsumerRebalanceListener

Stateless means processing of each message depends only on the message, so converting from JSON to Avro or filtering a stream are both stateless operations

ACLs are stored in Zookeeper node /kafka-acls/ by default.

GlobalKTables have their datasets replicated on each Kafka Streams instance and therefore no repartitioning is required