A social media analytics company runs a data processing application on a single Amazon EC2 On-Demand Instance. The application is stateless and processes user behavior data in near real-time. Recently, the application has started showing performance degradation during peak times, including 5xx errors due to high traffic volumes. The company wants to implement a solution to make the application scale automatically to handle traffic spikes in a cost-effective way. Which solution will meet these requirements MOST cost-effectively?