A company uses a mobile app on AWS to run online contests. The company selects a winner at random at the end of each contest. The contests run for variable lengths of time. The company does not need to retain any data from a contest after the contest is finished. The company uses custom code that is hosted on Amazon EC2 instances to process the contest data and select a winner. The EC2 instances run behind an Application Load Balancer and store contest entries on Amazon RDS DB instances. The company must design a new architecture to reduce the cost of running the contests. Which solution will meet these requirements MOST cost-effectively?