Which strategy should a solutions architect recommend to meet this requirement?

Explanations:

While ElastiCache can help with caching frequent queries, it introduces additional complexity and operational overhead for managing cache invalidation and consistency with DynamoDB. It doesn’t address cost reduction specifically, as it would add another service to manage and incur extra costs.

DynamoDB Accelerator (DAX) is a caching solution for DynamoDB, which can reduce read latency. However, it does not directly address the issue of cost reduction for the bulk of the data storage and retrieval. DynamoDB auto scaling can help with workload variation, but DAX and auto scaling together do not sufficiently optimize cost.

While provisioned capacity mode may be more cost-effective for predictable workloads, it does not address the bursty read patterns or repeated lookups in the scenario. Additionally, relying on auto scaling alone without using DAX may still result in high read costs. Savings Plans would not be as effective without optimizing the capacity mode and read/write patterns first.

Using DAX with provisioned capacity mode is ideal for reducing read costs in this scenario because DAX can cache frequently accessed data and reduce the need to hit DynamoDB for every lookup. Provisioned capacity mode allows for more predictable and cost-efficient usage, especially when combined with auto scaling for handling bursts of reads. This strategy directly targets cost reduction while optimizing performance.