Which AWS service should the company use?

Explanations:

AWS Step Functions is primarily used for orchestrating complex workflows and managing state across various AWS services. It does not provide message queuing or FIFO processing capabilities directly.

Amazon Simple Notification Service (SNS) is designed for pub/sub messaging and does not guarantee message ordering. It is suitable for broadcasting messages to multiple subscribers but not for FIFO message processing.

Amazon Kinesis Data Streams is designed for real-time data streaming and processing but does not inherently support FIFO message delivery. It focuses more on processing streams of data rather than traditional message queuing.

Amazon Simple Queue Service (SQS) provides FIFO queues that ensure messages are processed in the exact order they are sent. It supports reliable message storage, sending, and receiving, making it the ideal choice for the company’s requirements.