How can this be done with MINIMAL effort?

A company wants to identify specific Amazon EC2 instances that are underutilized and the estimated cost savings for each instance.

How can this be done with MINIMAL effort?
A . Use AWS Budgets to report on low utilization of EC2 instances.
B . Run an AWS Systems Manager script to check for tow memory utilization of EC2 instances.
C . Run Cost Explorer to look for low utilization of EC2 instances.
D . Use Amazon CloudWatch metrics to identify EC2 instances with low utilization.

Answer: C