Answer: EFS Standard-Infrequent Access (EFS Standard-IA)

## Explanation **EFS Standard-Infrequent Access (EFS Standard-IA)** is the most cost-effective option because: - **Multi-AZ requirement**: The question specifies data needs to be stored across multiple Availability Zones. EFS Standard and EFS Standard-IA both provide multi-AZ redundancy, while EFS One Zone and EFS One Zone-IA only store data in a single Availability Zone. - **Infrequent access pattern**: The data "will not be accessed regularly" - this is the perfect use case for infrequent access storage classes which offer lower storage costs for data that is accessed less frequently. - **Immediate retrievability**: EFS Standard-IA provides immediate access to data (unlike archival storage like Amazon S3 Glacier), meeting the requirement that data "must be immediately retrievable." - **Cost-effectiveness**: EFS Standard-IA offers lower storage costs than EFS Standard, while still providing the same multi-AZ durability and availability. The trade-off is higher per-GB access charges, but since the data is infrequently accessed, this results in overall cost savings. **Why not the other options:** - **EFS Standard**: More expensive for infrequently accessed data - **EFS One Zone**: Only single AZ, doesn't meet multi-AZ requirement - **EFS One Zone-IA**: Only single AZ, doesn't meet multi-AZ requirement

Author: Ritesh Yadav