Which cloud practice is illustrated by using AWS Cost Explorer to analyze resource usage and identify optimization opportunities?

Rightsizing is the practice of matching the appropriate instance types and sizes to your workload performance and capacity requirements at the lowest possible cost. AWS Cost Explorer helps identify underutilized resources (e.g., EC2 instances with low CPU utilization) that can be downsized or terminated, directly illustrating rightsizing. Reliability focuses on ensuring a system performs its intended function correctly and consistently, which is a broader concept than cost optimization. Resilience refers to a system's ability to recover from failures and maintain functionality, often involving redundancy and disaster recovery, not directly cost analysis. Modernization involves updating older applications or infrastructure to newer technologies, which might indirectly lead to cost savings but isn't the primary practice illustrated by analyzing current usage for optimization.