A Company Runs an Application That Uses Multiple Amazon EC2

Multiple Choice

A company runs an application that uses multiple Amazon EC2 instances to gather data from its users. The data is then processed and transferred to Amazon S3 for long-term storage. A review of the application shows that there were long periods of time when the EC2 instances were not being used. A solutions architect needs to design a solution that optimizes utilization and reduces costs. Which solution meets these requirements?

A) Use Amazon EC2 in an Auto Scaling group with On-Demand instances.
B) Build the application to use Amazon Lightsail with On-Demand Instances.
C) Create an Amazon CloudWatch cron job to automatically stop the EC2 instances when there is no activity.
D) Redesign the application to use an event-driven design with Amazon Simple Queue Service (Amazon SQS) and AWS Lambda.