A company has an application that is running on Amazon EC2 instances. A solutions architect has standardized the company on a particular instance family and various instance sizes based on the current needs of the company. The company wants to maximize cost savings for the application over the next 3 years. The company needs to be able to change the instance family and sizes in the next 6 months based on application popularity and usage. Which solution will meet these requirements MOST cost-effectively?

1. Compute Savings Plan
2. EC2 Instance Savings Plan
3. Zonal Reserved Instances
4. Standard Reserved Instances