Given the scenario where data is accessed infrequently (only twice each year), Amazon S3 Intelligent-Tiering is the most cost-effective option. This storage class automatically moves data between two access tiers (frequent and infrequent) when access patterns change. It is ideal for data with unknown or changing access patterns, and it can further reduce costs by moving infrequent access data to infrequent access tiers, while still providing rapid access when needed. Other options such as S3 Standard and S3 Glacier Instant Retrieval are either more costly or not optimized for such infrequently accessed data.