Resilience is the correct option.

Resilience describes an IT platform's capacity to continue functioning and remain reachable when it faces outages or unexpected disruptions. This concept covers design patterns and operational practices that allow systems to absorb faults, fail over to backups, and recover service with minimal interruption. It emphasizes continuity and recoverability during incidents rather than only preventing every possible failure.

Reliability is related but not the best choice because it emphasizes consistent and correct operation over time and measures like mean time between failures. Reliability focuses on reducing failures while resilience focuses on surviving and recovering when failures occur.

Cloud IAM is incorrect because it refers to identity and access management in cloud environments and deals with authentication and authorization. It does not describe platform availability or the ability to recover from outages.

Scalability is incorrect because it describes the ability to handle increased load by adding resources and improving performance. Scalability concerns capacity and growth and does not inherently ensure a system remains reachable during disruptions.

Full AWS Practitioner Certification Question