The correct answer is Amazon S3 Standard-Infrequent Access (S3 Standard-IA) because it provides a balance between availability, durability, and cost. It is designed for data that is less frequently accessed but requires rapid access when needed. Since the company frequently accesses the data only within the first 30 days, S3 Standard-IA is cost-effective for long-term storage with infrequent access. Amazon S3 Glacier and Amazon S3 Glacier Deep Archive, while cheaper, are designed for archival purposes and would not provide the rapid access required for the first 30 days. Amazon S3 Standard is designed for frequently accessed data and would be more expensive for the long-term storage where data is rarely accessed after the initial period.