Which pillar of the AWS Well-Architected Framework focuses on the ability to recover from failures and meet demand?

Correct answer: Reliability

Option D, Reliability, is correct because this pillar specifically addresses a workload's ability to recover from infrastructure or service disruptions, dynamically acquire computing resources to meet demand, and mitigate disruptions such as misconfigurations or transient network issues. Option A, Performance Efficiency, focuses on using computing resources efficiently to meet system requirements and maintaining that efficiency as demand changes and technologies evolve. Option B, Cost Optimization, is concerned with avoiding unnecessary costs and understanding where money is being spent, not with recovery or demand scaling. Option C, Security, covers protecting data, systems, and assets through risk assessments and mitigation strategies, which is distinct from failure recovery and demand management.