Which AWS service meets these requirements?

Explanations:

Amazon DynamoDB is a fully managed NoSQL database that provides consistent performance and low latency, typically in single-digit milliseconds, making it suitable for applications requiring such performance.

Amazon RDS is a managed relational database service that can provide good performance, but its latency can vary depending on factors like database size, instance type, and load, which may not consistently meet single-digit millisecond requirements.

Amazon Redshift is a data warehousing service optimized for analytics and complex queries, but it is not designed for single-digit millisecond latency due to its architecture and focus on batch processing rather than low-latency transactions.

Amazon EMR is a cloud big data platform for processing large amounts of data using frameworks like Apache Hadoop and Spark. It is not optimized for low-latency transactions, as it focuses on batch processing and analytics rather than real-time data access.