Which storage service should a solutions architect use to provide the MOST cost-effective solution?

A company runs an application on a group of Amazon Linux EC2 instances. The application writes log files using standard API calls. For compliance reasons, all log files must be retained indefinitely and will be analyzed by a reporting tool that must access all files concurrently.

Which storage service should a solutions architect use to provide the MOST cost-effective solution?
A . Amazon EBS
B . Amazon EFS
C . Amazon EC2 instance store
D . Amazon S3

Answer: D