Azure Cache for Redis Premium tier supports clustering. What does Redis clustering provide?

1. A Active geo-replication
2. ✓ B Horizontal sharding across multiple shards, each holding a subset of keys (correct answer)
3. C Automatic failover only
4. D Append-only persistence

Shortcut: Redis clustering splits the keyspace across multiple shards (nodes), enabling horizontal scaling of both memory and throughput beyond a single instance's limits.