A You can use Amazon Elasticache for Redis Sorted Sets to easily implement a dashboard that keeps a list of sorted data by their rank. https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/elasticache-use-cases.html#elasticache-for-redis-use-cases-gaming https://aws.amazon.com/elasticache/redis-vs-memcached/

To meet the requirements of caching frequently accessed data while adding the ability to sort or rank cached datasets, a developer should choose Amazon ElastiCache for Redis. ElastiCache is a web service that provides an in-memory data store in the cloud, and it supports both Memcached and Redis engines. While both engines are suitable for caching frequently accessed data, Redis is a better choice for this use case because it provides sorted sets and other data structures that allow for sorting and ranking of cached datasets. The data in ElastiCache can be encrypted at rest and in transit, ensuring the security of the PHI. Therefore, option A is the correct answer.

Sorted Sets in Elasticcache redis can do this job.

Redis is the best option to cached the results of queries and it also offer a encryption in-transit and at-rest

Redis: Supports various data structures such as strings, hashes, lists, sets, sorted sets, bitmaps, hyperloglogs, and geospatial indexes. Memcached: Primarily supports string-based keys and values; does not support advanced data structures.

ElastiCache for Redis also features Online Cluster Resizing, supports encryption, and is HIPAA eligible and PCI DSS compliant. https://aws.amazon.com/elasticache/redis-vs-memcached/