A pharmaceutical company has begun to explore using AWS cloud services for their computation workloads for processing incoming orders. Currently, they process orders on-premises using self-managed virtual machines with batch software installed. The current infrastructure design does not scale well and is cumbersome to update. In addition, each processed batch job takes roughly 30-45 minutes to complete. The processing times cannot be reduced due to the complexity of the application code, and they want to make the new solution as hands-off as possible with automatic scaling based on the number of queued orders.

Which AWS service would you recommend they use for this application design that best meets their needs and is cost optimized?