Using Amazon S3 with a lifecycle policy aligns with the data access pattern described and optimizes costs. Initially, Amazon S3 Standard handles the heavy access. After two weeks, moving the data to S3 Standard-Infrequent Access caters to sporadic access with lower costs. Finally, transitioning to Amazon S3 Glacier or S3 Glacier Deep Archive after 6 months addresses the legal retention requirement with the lowest cost option. Amazon Elastic File System (EFS) would not be suitable for archived data due to higher pricing for infrequently accessed files and is generally used for different use cases like file sharing or workload data. S3 Intelligent-Tiering is designed to automatically move data to the most cost-effective access tier without performance impact or operational overhead and could be a potential solution; however, the need for archival storage after 6 months is better served with manual transitioning to Glacier tiers, which offer cost benefits for data that is retained purely for compliance and not expected to be accessed.