A company ingests and processes streaming market data. The data rate is constant. A nightly process that calculates aggregate statistics takes 4 hours to complete. The statistical analysis is not critical to the business, and data points are processed during the next iteration if a particular run fails. The current architecture uses a pool of Amazon EC2 Reserved Instances with 1-year reservations. These EC2 instances run full time to ingest and store the streaming data in attached Amazon Elastic Block Store (Amazon EBS) volumes. A scheduled script launches EC2 On-Demand Instances each night to perform the nightly processing. The instances access the stored data from NFS shares on the ingestion servers. The script terminates the instances when the processing is complete. The Reserved Instance reservations are expiring. The company needs to determine whether to purchase new reservations or implement a new design. Which solution will meet these requirements MOST cost-effectively?