Which database should a solutions architect recommend?

Explanations:

Amazon RDS for MySQL is a relational database service that uses disk storage. While it provides features like automated backups and replication, it does not provide the in-memory capabilities needed for faster performance.

Amazon RDS for PostgreSQL is also a relational database service that relies on disk storage. It supports replication for high availability but lacks the in-memory architecture necessary for the required throughput improvements.

Amazon ElastiCache for Redis is an in-memory data store that provides low-latency data access and supports data replication for high availability. This makes it suitable for real-time data applications requiring high throughput.

Amazon ElastiCache for Memcached is an in-memory key-value store that offers high-speed performance but does not support data persistence or replication features as robustly as Redis. It is less suited for applications needing high availability.