Answer: Provisioned IOPS SSD Amazon Elastic Block Store (Amazon EBS) volume

## Explanation **Provisioned IOPS SSD Amazon EBS volume** is the correct choice because: 1. **Durable Storage**: Amazon EBS volumes are designed for durability with automatic replication within an Availability Zone, providing 99.999% availability. 2. **Consistent, Low-Latency Performance**: Provisioned IOPS SSD (io1/io2) volumes are specifically designed for I/O-intensive workloads that require consistent, low-latency performance. They allow you to provision a specific number of IOPS (Input/Output Operations Per Second) independent of volume size. 3. **Business-Critical Application**: EBS volumes are suitable for business-critical applications as they provide persistent storage that survives instance termination. **Why the other options are incorrect**: - **A. Instance store volume**: While instance store volumes can provide high performance, they are **ephemeral** (not durable) - data is lost when the instance is stopped or terminated. They don't meet the durability requirement. - **B. Amazon ElastiCache for Memcached cluster**: This is an in-memory caching service, not durable storage. Data in ElastiCache is volatile and can be lost if nodes fail or are restarted. - **D. Throughput Optimized HDD Amazon EBS volume**: These are designed for large, sequential workloads (like big data, data warehouses) but have higher latency and are not optimized for low-latency, random I/O operations that typical business-critical applications require. **Key AWS Concepts**: - **EBS Volume Types**: - **Provisioned IOPS SSD (io1/io2)**: High performance, low latency, consistent I/O - **General Purpose SSD (gp2/gp3)**: Balanced price and performance - **Throughput Optimized HDD (st1)**: Low-cost HDD for throughput-intensive workloads - **Cold HDD (sc1)**: Lowest cost for infrequently accessed data For business-critical applications requiring both durability and consistent low-latency performance, Provisioned IOPS SSD EBS volumes are the recommended solution.

Author: LeetQuiz Editorial Team