Which of the following is a pillar of the AWS Well-Architected Framework?

Explanations:

Redundancy is not a pillar; it is a technique used within the Reliability pillar.

Operational excellence is one of the five pillars of the AWS Well-Architected Framework.

Availability is a key concept within the Reliability pillar, but it is not a standalone pillar.

Multi-Region is a strategy to improve resilience and availability, but it is not a pillar.