A company has multiple Amazon EC2 instances that run a resource-intensive application in a development environment. A SysOps administrator is implementing a solution to stop these EC2 instances when they are not in use.
Which solution will meet this requirement?

A. Assess AWS CloudTrail logs to verify that there is no EC2 API activity. Invoke an AWS lambda function to stop the EC2 instances.
B. Create an Amazon CloudWatch alarm to stop the EC2 instances when the average CPU utilization is lower than 5% for a 30-minute period.
C. Create an Amazon CloudWatch metric to stop the EC2 instances when the VolumeReadBytes metric is lower than 500 for a 30-minute period.
D. Use AWS Config to invoke an AWS Lambda function to stop the EC2 instances based on resource configuration changes.