What should the solutions architect recommend?

Explanations:

Installing MySQL on Amazon EC2 in the secondary Region does not inherently provide read replication capabilities or latency improvements. It would require significant management overhead, and latency will depend on the network configuration and not necessarily guarantee less than 1 second of latency for reads.

Migrating the database to Amazon Aurora with cross-Region replicas provides the ability to have low-latency read replicas in a secondary Region. Aurora is designed for high availability and performance, and its cross-Region replication is optimized for low-latency reads, meeting the requirement of less than 1 second of replication latency.

Creating another RDS for MySQL read replica in the secondary Region may not achieve the desired latency. MySQL read replicas typically experience higher replication lag compared to Aurora’s cross-Region replicas. This option may not guarantee the less than 1 second latency requirement.

Implementing Amazon ElastiCache can help improve application performance by caching frequent queries, but it does not address the underlying issue of read replication latency. While it can reduce load on the database, it does not provide a solution for reducing the read latency from the secondary Region.