Which AWS service is a target for sizing recommendations from AWS Compute Optimizer based on workload metrics?

Amazon EC2 is the correct answer because AWS Compute Optimizer provides sizing recommendations for various AWS resources, with Amazon EC2 instances being a primary target. It analyzes historical utilization metrics to suggest optimal EC2 instance types and sizes, aiming to reduce costs and improve performance. Amazon RDS is incorrect because while Compute Optimizer can provide recommendations for it, EC2 is a more prominent and foundational service for which it offers detailed sizing. Amazon Lightsail is incorrect as it's a simplified service for which Compute Optimizer does not typically provide detailed sizing recommendations. AWS Step Functions is incorrect because it is a serverless workflow service, not a compute resource that requires sizing recommendations in the same way EC2 instances do.