A company wants to provide data scientists with near real-time read-only access to the company's production Amazon RDS for PostgreSQL database. The database is currently configured as a Single-AZ database. The data scientists use complex queries that will not affect the production database. The company needs a solution that is highly available. Which solution will meet these requirements MOST cost-effectively?

The correct answer is to change the setup from a Single-AZ to a Multi-AZ cluster deployment with two readable standby instances and provide read endpoints to the data scientists. This is the most cost-effective solution because Multi-AZ clusters for PostgreSQL provide two readable standby instances in different Availability Zones. These standby instances can be used for read traffic, offloading complex queries from the primary instance without impacting its performance. This also inherently provides high availability. Scaling the existing production database (incorrect option 1) would increase costs unnecessarily and still risk performance impact from complex queries. Changing to a Multi-AZ instance deployment with a larger secondary standby (incorrect option 2) is not ideal because the secondary standby in a Multi-AZ instance deployment is not directly readable. Providing two additional read replicas (incorrect option 3) would be more expensive than utilizing the readable standbys already provided by a Multi-AZ cluster deployment.