An e-commerce application uses multiple Lambda functions where each function performs a specific step in an order workflow. The functions must run in a defined sequence. Which solution ensures the functions execute in order with the least operational overhead?

AWS Step Functions is the most suitable solution because it is designed for orchestrating multi-step workflows involving serverless functions like Lambda. It allows you to define a state machine that explicitly controls the order of execution, handles retries, error handling, and parallel execution, all with minimal operational overhead. Using an SQS queue would require complex logic within each Lambda function to manage state and ensure sequential processing, increasing operational overhead. SNS is a publish/subscribe service and is not designed for sequential workflow orchestration; while subscription filters can route messages, they don't enforce a specific execution order across multiple steps in a workflow. Amazon EventBridge Scheduler is for scheduling events at specific times or intervals, not for orchestrating a sequential workflow based on the completion of previous steps.