A solution architect is planning a deployment of Amazon ElastiCache for Redis with cluster mode enabled. Each shard is planned to have 5 read replicas. What is the maximum number of shards that can be deployed?

Answer options:

A.5
B.15
C.90
D.450

Answer: B
A deployment of Amazon ElastiCache for Redis with cluster mode enabled can have a maximum of 90 nodes. Each shard can consist of one primary node and up to five read replica nodes. Thus, with five read replicas, each shard consists of six nodes in total. This means that with five read replicas per shard, the maximum number of shards is 15. Therefore, Option B is CORRECT, and other options are incorrect.
Reference:
https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Replication.html
https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Replication.Redis-RedisCluster.html