AWS Certified Developer Associate (#4)

An organization is storing large files in Amazon S3, and is writing a web application to display meta-data about the files to end-users. Based on the metadata a user selects an object to download. The organization needs a mechanism to index the files and provide single-digit millisecond latency retrieval for the metadata. What AWS service should be used to accomplish this?

Amazon DynamoDB
Amazon EC2
AWS Lambda
Amazon RDS