A company runs a nightly batch video-transcoding job on a fleet of EC2 instances. The job is stateless, writes results to Amazon S3 as each file completes, and can restart individual tasks from a queue if an instance is lost. The finance team wants the SysOps administrator to reduce compute costs for this workload by as much as possible while keeping the job able to complete within its overnight window. Which purchasing option should be used for the transcoding instances?