A company runs a fleet of 40 On-Demand EC2 instances hosting an internal application. Finance reports the monthly EC2 bill is high, and the operations team suspects the instances were oversized during initial deployment. Average CPU utilization sits around 8% and memory usage around 20%. The team wants specific, data-driven recommendations on which instance types to move to, based on actual historical usage, before making any changes. Which AWS service should they use to obtain these recommendations at the lowest effort?