Answer: Elasticity

## Explanation **Elasticity** is the correct answer because it refers to the ability to automatically scale computing resources up or down based on demand. This concept allows organizations to: 1. **Acquire resources when needed** - Scale out to handle increased workloads 2. **Release resources when no longer needed** - Scale in to reduce costs when demand decreases **Key AWS services that enable elasticity:** - **Amazon EC2 Auto Scaling** - Automatically adjusts the number of EC2 instances - **AWS Auto Scaling** - Unified scaling across multiple AWS services - **Elastic Load Balancing** - Distributes traffic across multiple instances **Why the other options are incorrect:** - **Availability (B)**: Refers to the ability of a system to remain operational and accessible. It's about uptime and redundancy, not resource scaling. - **Reliability (C)**: Refers to a system's ability to recover from failures and continue functioning. It's about fault tolerance and disaster recovery. - **Durability (D)**: Refers to the long-term protection of data, ensuring it doesn't get lost or corrupted over time. **Real-world example**: An e-commerce website that needs more servers during holiday sales (scale out) and fewer servers during regular periods (scale in) demonstrates elasticity.

Author: Ritesh Yadav