An application using Amazon RDS experiences periodic read-heavy traffic spikes that degrade query performance. The team wants a multithreaded, scalable caching solution to offload read requests and improve performance with the least complexity. Which option is the simplest appropriate solution?

Amazon ElastiCache for Memcached is the simplest appropriate solution because it is designed for high-performance, multithreaded caching of frequently accessed data, making it ideal for offloading read-heavy traffic spikes from a database. Its object caching capabilities directly address the need to improve query performance. Replicating data to DynamoDB with DAX is overly complex and expensive for this specific problem, as it involves migrating data to a different database system. Configuring Multi-AZ with a single standby does not offload read requests; the standby is for high availability, not read scaling. While ElastiCache for Redis can also offload reads, Memcached is generally simpler for basic object caching and is multithreaded, which aligns with the "multithreaded, scalable caching solution" requirement.