A mobile app allows users to submit photos, which are stored in an Amazon S3 bucket. Currently, a batch of Amazon EC2 Spot Instances is launched nightly to process all the day’s uploads. Each photo requires approximately 3 minutes and 512 MB of memory to process. To improve responsiveness and minimize costs, the company wants to shift to near real-time image processing that begins as soon as an image is uploaded. Which solution will provide the MOST cost-effective and scalable architecture to meet these new requirements?