OCI Streaming consumer groups assign each stream partition exclusively to one consumer-group instance at a time. Oracle states that every partition is owned by one instance following a successful rebalance and that instances exceeding the number of available partitions remain idle. With eight partitions, no more than eight of the twelve consumer instances can actively consume simultaneously, leaving four without assignments. This is not a fixed eight-consumer limitation: increasing the stream to twelve or more partitions could allow all twelve instances to become active. Consumer groups automatically coordinate partition assignment, offsets, commits, heartbeats, and rebalancing, so Service Connector Hub is unnecessary. Stream pools likewise do not determine the consumer-to-partition scaling relationship. Therefore, B explains the observed behavior precisely.