A company will store data in AWS that is rarely accessed. When access is needed, the data must be retrievable within 12 hours. The company wants the lowest possible storage cost per gigabyte. Which Amazon S3 storage class satisfies these requirements?

S3 Glacier Flexible Retrieval is the correct choice because it offers the lowest storage cost per gigabyte for infrequently accessed data, with retrieval options that can be as fast as minutes or up to 12 hours, satisfying the requirement. S3 Standard is for frequently accessed data and has higher storage costs. S3 One Zone-IA and S3 Standard-IA are designed for data that is accessed less frequently than S3 Standard but still requires rapid access (milliseconds), and their storage costs are higher than S3 Glacier Flexible Retrieval.