A database specialist is designing an enterprise application for a large company. The application uses Amazon DynamoDB with DynamoDB Accelerator (DAX). The database specialist observes that most of the queries are not found in the DAX cache and that they still require DynamoDB table reads.
What should the database specialist review first to improve the utility of DAX?

A. The DynamoDB ConsumedReadCapacityUnits metric
B. The trust relationship to perform the DynamoDB API calls
C. The DAX cluster's TTL setting
D. The validity of customer-specified AWS Key Management Service (AWS KMS) keys for DAX encryption at rest